Replace numba generated jit

[mcocdawc]

Replaces deprecated numba generated_jit with overload

Cleans up many other warnings from pandas and numpy about deprecated behaviour.

Solves #76

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.71429% with 16 lines in your changes are missing coverage. Please review.

Project coverage is 66.31%. Comparing base (55ac9f1) to head (670c0f4).

Files	Patch %	Lines
...oord/cartesian_coordinates/_cart_transformation.py	50.00%	13 Missing :warning:
src/chemcoord/cartesian_coordinates/_indexers.py	93.33%	2 Missing :warning:
src/chemcoord/internal_coordinates/_indexers.py	94.73%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #94 +/- ## ========================================== + Coverage 65.11% 66.31% +1.20% ========================================== Files 26 27 +1 Lines 2763 2808 +45 ========================================== + Hits 1799 1862 +63 + Misses 964 946 -18 ```

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[mcocdawc]

Still todo

• [x] Update supported python versions in documentation
• [x] Introduce some more tests, to ensure new code is covered
• [x] Fix the explicit cast warnings also for users calling the code
• [x] Update Readme in compiled doc