fix(banner): Improve GH banner copy (#91748)

Just update the GH Auth banner copy

Author: Adal3n3

src/sentry/auth/providers/github/constants.py

@@ -6,7 +6,7 @@
 
 REQUIRE_VERIFIED_EMAIL = settings.GITHUB_REQUIRE_VERIFIED_EMAIL
 
-ERR_NO_ORG_ACCESS = "You do not have access to the required GitHub organization."
+ERR_NO_ORG_ACCESS = "Your GitHub account must be a member of the linked organization to access this Sentry organization. Contact your admin to request access."
 
 ERR_NO_PRIMARY_EMAIL = (
     "We were unable to find a primary email address associated with your GitHub account."