Use --extras all in latest deps mypy CI

Twisted trunk job already does this.

Missed in #12531.

Author: David Robertson

Diff for: .github/workflows/latest_deps.yml

@@ -32,6 +32,7 @@ jobs:
         with:
           python-version: "3.x"
           poetry-version: "1.2.0b1"
+          extras: "all"
       # Dump installed versions for debugging.
       - run: poetry run pip list > before.txt
       # Upgrade all runtime dependencies only. This is intended to mimic a fresh