Agilent33250a.py fix

[dschuechter]

Fixing a small leftover from python 2 times. In python 3 string.atof() is not supported anymore and can be replaced by float().

[codecov[bot]]

Codecov Report

Base: 35.90% // Head: 35.90% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (3d2f5a7) compared to base (26fcc9f). Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #191 +/- ## ======================================= Coverage 35.90% 35.90% ======================================= Files 79 79 Lines 5284 5283 -1 ======================================= Hits 1897 1897 + Misses 3387 3386 -1 ``` | [Impacted Files](https://codecov.io/gh/SiLab-Bonn/basil/pull/191?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SiLab-Bonn) | Coverage Δ | | |---|---|---| | [basil/HL/agilent33250a.py](https://codecov.io/gh/SiLab-Bonn/basil/pull/191?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SiLab-Bonn#diff-YmFzaWwvSEwvYWdpbGVudDMzMjUwYS5weQ==) | `0.00% <0.00%> (ø)` | | 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=SiLab-Bonn). 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=SiLab-Bonn)

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[leloup314]

Thanks for the PR! As you can see, flake8 is failing because now the imported string is unused. Could you remove the import? This should fix the flake8 job

[dschuechter]

Updated!

[leloup314]

Very nice, thank you for contributing!