Drop support for protobuf v5 #430
Description
Do we actually want to keep supporting v5?
According to the documentation, it is maintenance-only (https://protobuf.dev/support/version-support) and support will end at the end of the month (https://protobuf.dev/support/version-support/#python)
Originally posted by @AdrienVannson in #429 (comment)
It probably makes sense to drop support for protobuf==5.* in some future release, although we ought to take a look at support across the ecosystem.