release_2.1.1rc0

User API Changes

• Revert premature deprecation of sources field for
  python_awslambda (#11217)

Bugfixes

• Move graph cycle detection to Rust to fix recursion limit.
  (cherrypick of #11202) (#11204)
• Set the soft ulimit value more conservatively to fix macOS Big Sur
  issue (cherrypick of #11194) (#11197)