Make guild member check case-insensitive in PR labeler (#54444)

Fixes the casing of the remaining names and adjust the script to allow
any casing of handles.

Release Notes:

- N/A
dd5cf89e03Joseph T. Lyons committed on 4/21/2026, 8:02:59 PM· committed by GitHubparentce08d96
1 file changedLine totals unavailable