Ruby 3.0 and Ruby 2.7 are dropped because it is not compatible with Ubuntu 22.04 (Jammy Jellyfish) that ships with OpenSSL 3 and OpenSSL 3 support is available only for Ruby 3.1 or higher
We decided to not backport openssl-3.x gem into ruby_2_7 and ruby_3_0 branches. Because it affects with OpenSSL 1.0.x.
CI against Oracle Database 11g will be migrated to GitHub Actions via https://github.com/rsim/oracle-enhanced/pull/2327
that runs all Ruby versions supported by Rails main branch, so removing Ruby 2.7 and 3.0 here should be safe.
Refer to https://bugs.ruby-lang.org/issues/18658
CI against Oracle Database 11g will be migrated to GitHub Actions via https://github.com/rsim/oracle-enhanced/pull/2327 that runs all Ruby versions supported by Rails main branch, so removing Ruby 2.7 and 3.0 here should be safe.