* Update third_party/protobuf
* run tools/distrib/python/make_grpcio_tools.py
* regenerate protos for ruby, php
* update build_handwritten.yaml
* regenerate projects
* Build - Use :well_known_type_protos instead of :well_known_protos
* Fix target
* Update upb
* Update Python for Protobuf 4.21 (#140)
* Update protobuf dependency on grpcio-tools
* Off by one
* Drop python 3.6 support
* Try upgrading pip
* And in the other script
* Try to figure out if we're compatible with abi3
* See what we've already got installed
* Update the requirements.txt file I didn't know existed
* And here too
* See what's installed
* Let's try that again
* Remove
* Try to confirm version
* Let me see the generated code
* Fix non-Bazel test runner
* Work for all test directories
* Regenerate example protos
* Clean up
* Generate .pyi files
* Fix type checking and linting
* Exclude pyi files from isort
* Upgrade to 3.21.4
* Update iwyu to get around messy protobuf IWYU rules
Co-authored-by: Richard Belleville <gnossen@gmail.com>