[CI] Drop testing for Ruby 3.0 (EOL'ed)

Author: picandocodigo

.buildkite/pipeline.yml

@@ -33,7 +33,6 @@ steps:
           - "3.3"
           - "3.2"
           - "3.1"
-          - "3.0"
         ruby_source:
           - "ruby"
         transport:

.github/workflows/main.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '3.0', '3.1', '3.2', '3.3', 'jruby-9.3', 'jruby-9.4' ]
+        ruby: ['3.1', '3.2', '3.3', 'jruby-9.3', 'jruby-9.4']
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4