chore: bump contributor check AGT to v4.1.0 (#2484)

Update contributor-check workflow to fetch AGT scripts from v4.1.0.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 4b935b0a-90c8-454f-958f-93b468fd4e17

Author: aaronpowell

.github/workflows/contributor-check.yml

@@ -31,7 +31,7 @@ jobs:
 
       - name: Fetch AGT check scripts
         env:
-          AGT_REF: v3.4.0
+          AGT_REF: v4.1.0
         run: |
           mkdir -p /tmp/agt
           curl -fsSL "https://raw.githubusercontent.com/microsoft/agent-governance-toolkit/${AGT_REF}/scripts/contributor_check.py" \