replace deprecated `np.float` dtype with `float`

[Ab2nour]

Description

np.float is deprecated since numpy 1.20.0. I replaced np.float with float (as suggested in the Numpy docs).

Related issues or pull requests

Fixes #1016

Pull Request Checklist

• [ ] Added a note about the modification or contribution to the ./docs/sources/CHANGELOG.md file (if applicable)
• [ ] Added appropriate unit test functions in the ./mlxtend/*/tests directories (if applicable)
• [ ] Modify documentation in the corresponding Jupyter Notebook under mlxtend/docs/sources/ (if applicable)
• [x] Ran PYTHONPATH='.' pytest ./mlxtend -sv and make sure that all unit tests pass (for small modifications, it might be sufficient to only run the specific test file, e.g., PYTHONPATH='.' pytest ./mlxtend/classifier/tests/test_stacking_cv_classifier.py -sv)
• [x] Checked for style issues by running flake8 ./mlxtend

[rasbt]

Thanks for the PR, appreciate it!

[codecov[bot]]

Codecov Report

Base: 77.33% // Head: 77.33% // No change to project coverage :thumbsup:

Coverage data is based on head (8b5562d) compared to base (061fdb1). Patch coverage: 25.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1018 +/- ## ======================================= Coverage 77.33% 77.33% ======================================= Files 198 198 Lines 11171 11171 Branches 1461 1461 ======================================= Hits 8639 8639 Misses 2318 2318 Partials 214 214 ``` | [Impacted Files](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka) | Coverage Δ | | |---|---|---| | [mlxtend/\_base/\_base\_model.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9fYmFzZS9fYmFzZV9tb2RlbC5weQ==) | `50.00% <0.00%> (ø)` | | | [mlxtend/\_base/tests/test\_classifier.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9fYmFzZS90ZXN0cy90ZXN0X2NsYXNzaWZpZXIucHk=) | `91.93% <ø> (ø)` | | | [mlxtend/classifier/adaline.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL2FkYWxpbmUucHk=) | `100.00% <ø> (ø)` | | | [mlxtend/classifier/ensemble\_vote.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL2Vuc2VtYmxlX3ZvdGUucHk=) | `71.60% <ø> (ø)` | | | [mlxtend/classifier/logistic\_regression.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL2xvZ2lzdGljX3JlZ3Jlc3Npb24ucHk=) | `100.00% <ø> (ø)` | | | [mlxtend/classifier/multilayerperceptron.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL211bHRpbGF5ZXJwZXJjZXB0cm9uLnB5) | `100.00% <ø> (ø)` | | | [mlxtend/classifier/oner.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL29uZXIucHk=) | `87.01% <ø> (ø)` | | | [mlxtend/classifier/perceptron.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL3BlcmNlcHRyb24ucHk=) | `97.36% <ø> (ø)` | | | [mlxtend/classifier/softmax\_regression.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL3NvZnRtYXhfcmVncmVzc2lvbi5weQ==) | `100.00% <ø> (ø)` | | | [mlxtend/classifier/stacking\_classification.py](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka#diff-bWx4dGVuZC9jbGFzc2lmaWVyL3N0YWNraW5nX2NsYXNzaWZpY2F0aW9uLnB5) | `100.00% <ø> (ø)` | | | ... and [47 more](https://codecov.io/gh/rasbt/mlxtend/pull/1018?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Sebastian+Raschka)

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