Pin JRuby 9.4.10.0 to prevent build error on JRuby 9.4.11.0

As a workaround, the JRuby CI matrix is pinned to 9.4.10.0.
The issue has been reported at jruby/jruby#8606.

https://github.com/bblimke/webmock/actions/runs/13170199216/job/36759013080

Author: koic

.github/workflows/CI.yml

@@ -21,7 +21,10 @@ jobs:
           - '3.0'
           - '2.7'
           - '2.6'
-          - jruby-head
+          # FIXME: When the JRuby issue https://github.com/jruby/jruby/issues/8606 is resolved,
+          # please replace it with the following:
+          # ruby-version: 'jruby-head' # Latest stable JRuby version
+          - 'jruby-9.4.10.0' # The latest JRuby version that passes CI
     continue-on-error: ${{ matrix.ruby == 'head' || matrix.ruby == 'jruby-head' }}
     name: Ruby ${{ matrix.ruby }}
     env: