Increase agent timeout to 45 minutes

The agent timed out at the default 20 minutes while fetching release
notes, editing the matrix, running table validation, and iterating
on fixes. 45 minutes gives adequate headroom for this multi-step task.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: felickz

.github/workflows/update-ghas-matrix.lock.yml

@@ -7,6 +7,7 @@ permissions:
   contents: read
   pull-requests: read
   issues: read
+timeout-minutes: 45
 tools:
   github:
     toolsets: [default]