Fix Pyright strictness errors (`reportUnusedCallResult` and `reportAny`) in `manifest.py` and `git_utils.py`

[UweSchwaeke]

While running strict Pyright type checking (moving away from standard Pylance defaults), several type-checking violations were uncovered. These aren't necessarily runtime bugs, but fixing them will make our codebase strictly typed and prevent future regressions.

The errors fall into two categories: unused return values and un-annotated Any types.