Fix JRuby and ruby-head builds

JRuby needs an older ubuntu.
Ruby >3.4 no longer has benchmark as default gem.

Author: eval

.github/workflows/test.yml

@@ -10,30 +10,39 @@ on:
 jobs:
   ruby:
     name: ${{ matrix.ruby }} (timeout ${{ matrix.timeout }})
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     timeout-minutes: ${{ matrix.timeout }}
     strategy:
       fail-fast: false
       matrix:
        include:
          - ruby: 3.1
            timeout: 5
+           os: ubuntu-latest
          - ruby: 3.2
            timeout: 5
+           os: ubuntu-latest
          - ruby: 3.3
            timeout: 5
+           os: ubuntu-latest
          - ruby: ruby
            timeout: 5
+           os: ubuntu-latest
          - ruby: head
            timeout: 5
+           os: ubuntu-latest
          - ruby: truffleruby
            timeout: 50
+           os: ubuntu-latest
          - ruby: truffleruby-head
            timeout: 50
+           os: ubuntu-latest
          - ruby: jruby
            timeout: 5
+           os: ubuntu-22.04
          - ruby: jruby-head
            timeout: 5
+           os: ubuntu-22.04
     steps:
     - name: Installing libyaml-dev
       run: |

Gemfile

@@ -11,3 +11,5 @@ gem 'jruby-openssl', :platforms => :jruby
 gem 'mini_mime'
 
 gem 'byebug', :platforms => :mri
+
+gem "benchmark"