gitlab-ci: Update to Fedora 34, add gRPC to Debian

Brad Kingrequested to merge
brad.king/cmake:ci-fedora34 into master

Also:

  • Add Qt 6 for later use
  • Add codespell for later use
  • Add gRPC and enable FindProtobuf gRPC tests for !6068 (merged).
Edited by Brad King

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