Protobuf is not going to have new binary build anytime soon

So just don't test on Ruby 3.3 this gem yet. An alternative is to mess
around with Ruby platform and let it compile each time. Probably
de-optimizes older Ruby versions, which have a precompiled binaries
already.

support/ci/generate

@@ -181,7 +181,7 @@ class CI
         matrix:
           join(
             generate(
-              ruby_version(MRI_RUBY),
+              ruby_version(MRI_RUBY.drop(1)),
               bundle_gemfile(GEMFILE, GEMFILE_RAILS_6_1, GEMFILE_RAILS_6_0),
               database_url(SQLITE3)
             )