Support parsing of CODEOWNERS entries containing the ^ character

[juanis2112]

Hi 👋,

I encountered a parsing error when using codeowners.ParseFile() while running OpenSSF Scorecards. The failure occurs when the CODEOWNERS file contains an entry with the ^ character (e.g., IBM/vllm). Currently, this character isn’t allowed by the parsing rules, which causes parsing to abort.

I think it might be worth expanding the parsing rules to include ^ as a valid owner or pattern character. My guess is that the fix needs to be done in the isPatternChar function.

I'm happy to open a PR to add support for ^ (including tests) if this aligns with the project’s direction. Please let me know if you'd like me to proceed.