Fix link to PermissionHandlerEnums.h

Update the link to the PermissionHandlerEnums.h

Pre-launch Checklist

[x] I made sure the project builds.
[x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
[ ] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is does not need version changes.
[ ] I updated CHANGELOG.md to add a description of the change.
[ ] I updated/added relevant documentation (doc comments with ///).
[x] I rebased onto main.
[ ] I added new tests to check the change I am making, or this PR does not need tests.
[x] I made sure all existing and new tests are passing.
[x] I ran dart format . and committed any changes.
[x] I ran flutter analyze and fixed any errors.