Update version number, changelog and notebooks for 1.5.2 release

[w-k-jones]

• [x] Have you followed our guidelines in CONTRIBUTING.md?
• [x] Have you self-reviewed your code and corrected any misspellings?
• [x] Have you written documentation that is easy to understand?
• [x] Have you written descriptive commit messages?
• [x] Have you added NumPy docstrings for newly added functions?
• [x] Have you formatted your code using black?
• [x] If you have introduced a new functionality, have you added adequate unit tests?
• [x] Have all tests passed in your local clone?
• [x] If you have introduced a new functionality, have you added an example notebook?
• [x] Have you kept your pull request small and limited so that it is easy to review?
• [x] Have the newest changes from this branch been merged?

[github-actions[bot]]

Linting results by Pylint:

Your code has been rated at 8.72/10 (previous run: 8.72/10, +0.00) _{The linting score is an indicator that reflects how well your code version follows Pylint’s coding standards and quality metrics with respect to the RC_v1.5.x branch. A decrease usually indicates your new code does not fully meet style guidelines or has potential errors.}

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (81ea461) 56.91% compared to head (47bd890) 56.91%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## RC_v1.5.x #381 +/- ## ========================================== Coverage 56.91% 56.91% ========================================== Files 20 20 Lines 3440 3440 ========================================== Hits 1958 1958 Misses 1482 1482 ``` | [Flag](https://app.codecov.io/gh/tobac-project/tobac/pull/381/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tobac-project) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/tobac-project/tobac/pull/381/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tobac-project) | `56.91% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tobac-project#carryforward-flags-in-the-pull-request-comment) to find out more.

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