Change GitHub CI to install JRuby 9.2 on Ubuntu 20.04

Author: piotrmurach

.github/workflows/ci.yml

@@ -32,7 +32,6 @@ jobs:
           - "3.2"
           - "3.3"
           - ruby-head
-          - jruby-9.2
           - jruby-9.3
           - jruby-9.4
           - jruby-head
@@ -42,6 +41,8 @@ jobs:
             os: ubuntu-20.04
           - ruby: "2.7"
             coverage: true
+          - ruby: jruby-9.2
+            os: ubuntu-20.04
     env:
       COVERAGE: ${{ matrix.coverage }}
       COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}