docs: update links to PythonCall & JuliaCall

[codecov[bot]]

Codecov Report

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

Project coverage is 73.70%. Comparing base (d11e61d) to head (0e7a455). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #71 +/- ## ========================================== - Coverage 74.06% 73.70% -0.37% ========================================== Files 4 4 Lines 1666 1605 -61 ========================================== - Hits 1234 1183 -51 + Misses 432 422 -10 ```

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