Fix CI

[chinwobble]

Fix the broken CI.

• add fail-fast: false. If ci on mac fails, it won't stop building on linux. This is useful to check if one builds but the other doesn't
• Pin the image versions. macos-latest automatically updated to m1 mac on arm64 which was caused the CI to start failing
• Pin the versions of the ubuntu-24.04 so that it doesn't automatically update and randomly fail when a new latest is released
• Fix the ci trigger so that ci is always on pull requests
• Fix the incremental builds header file changes are detected properly.