chore: hide noisy build log warnings

[mcoliver]

Local build logs are incredibly noisy and often surpass 100,000 lines. Hiding these two specific warnings cleans up over 10% of the log lines. Pyside6 builds alone produce over 12,000 lines of these warnings

/Users/moliver/dev/_openrv/OpenRV/_build/_deps/rv_deps_pyside6-src/build/.venv/build/pyside6/PySide6/QtCore/PySide6/QtCore/qtimer_wrapper.cpp:1198:18: warning: cast from 'PyObject *(*)(PyObject *)' (aka '_object *(*)(_object *)') to 'PyCFunction' (aka '_object *(*)(_object *, _object *)') converts to incompatible function type [-Wcast-function-type-mismatch]
 1198 |     {"interval", reinterpret_cast<PyCFunction>(Sbk_QTimerFunc_interval), METH_NOARGS, nullptr},
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Adding

…no-cast-function-type-mismatch (GCC/Clang)
-Wno-deprecated-declarations (GCC/Clang)
/wd4996 (MSVC equivalent for deprecated declarations)

Linked issues

Summarize your change.

Describe the reason for the change.

Describe what you have tested and on which operating system.

Add a list of changes, and note any that might need special attention during the review.

If possible, provide screenshots.