Update CI to use ubuntu-22.04

Author: jterapin

.github/workflows/ci.yml

@@ -20,7 +20,8 @@ jobs:
       fail-fast: false
       matrix:
         ruby: [2.5, 2.6, 2.7, '3.0', 3.1, 3.2, 3.3, jruby-9.2, jruby-9.3, jruby-9.4]
-    runs-on: ubuntu-latest
+    # change to ubuntu-latest once Ruby 2.5 and JRuby 9.2 is dropped
+    runs-on: ubuntu-22.04
     steps:
       - uses: ruby/setup-ruby@v1
         with: