Bump version

[gdalle]

Checklist

• [x] Appropriate tests were added
• [x] Any code changes were done in a way that does not break public API
• [x] All documentation related to code changes were updated
• [x] The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• [x] Any new documentation only uses public API

Additional context

Bump version to 3.12 for release

[codecov[bot]]

Codecov Report

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

Project coverage is 85.70%. Comparing base (17bb8a8) to head (452f4da). Report is 11 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #429 +/- ## ========================================== - Coverage 86.30% 85.70% -0.60% ========================================== Files 47 47 Lines 2913 2904 -9 ========================================== - Hits 2514 2489 -25 - Misses 399 415 +16 ```

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