Fix GitHub Actions CI builds

[Konstantysz]

Summary

• Fix SDL2 compatibility by building from source for Linux wheels
• Update deprecated Windows runners to windows-2022
• Fix POSIX/GNU source compatibility for strdup/realpath
• Remove non-existent pillow dependency from MSYS2 build
• Update MSBuild path for Visual Studio 2022

Changes

SDL2 Compatibility (#935)

• Build SDL2 2.0.22 from source in manylinux environment
• Required for touchpad API support (SDL >= 2.0.14)
• Adds ~5-10 min to Linux wheel build time

Windows Runner Updates

• Replace deprecated windows-2019 with windows-2022 (3 occurrences)
• Update MSBuild path from VS 2019 to VS 2022 for MSYS builds

Linux Build Compatibility

• Use _GNU_SOURCE instead of _POSIX_C_SOURCE for broader compatibility
• Fixes implicit declaration errors for strdup/realpath functions

MSYS2 Dependencies

• Remove non-existent mingw-w64-${{matrix.arch}}-python-pillow package

Documentation

• Add build requirements section to README.rst
• Document SDL2 version requirements for source builds

[Frostbyte0x70]

Thank you for looking into this! The x64 Mac build does indeed get stuck. Looking at older logs, it seems like it's out of support now. Could you try bumping it to macos-13? That's the version we use for the x64 Mac build on other repos and it seems to work fine there.

[Konstantysz]

Thank you for looking into this! The x64 Mac build does indeed get stuck. Looking at older logs, it seems like it's out of support now. Could you try bumping it to macos-13? That's the version we use for the x64 Mac build on other repos and it seems to work fine there.

@Frostbyte0x70 I bumped up macos :)

[Frostbyte0x70]

Thanks again!