Add torch 0.17 / libtorch 2.8 compatibility

[Chandraveersingh1717]

Closes #27

Updated torchvisionlib to work with {torch} 0.17 (libtorch 2.8) by aligning with the corresponding pytorch/vision version.

Changes:

• Updated GIT_TAG to v0.23.0 in CMakeLists.txt
• Removed the decode_png patch since 16-bit PNG support is now available upstream
• Updated CI to use CUDA 12.6 instead of 11.8
• Fixed deprecated ::set-output usage in GitHub Actions
• Bumped package version to 0.7.0

[dfalbel]

Thanks @Chandraveersingh1717, I've moved to #29 and fixed remaining issues.