Remove JRuby from the test matrix

It's not even booting the test suite for unclear reason.
I don't have the time to investigate it. If someone care
about JRuby coverage, PR welcome.

Author: byroot

.github/workflows/test.yaml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["3.4", "3.3", "3.2", "3.1", "3.0", "2.7", "2.6", "jruby"]
+        ruby: ["3.4", "3.3", "3.2", "3.1", "3.0", "2.7", "2.6"]
     runs-on: ubuntu-latest
     env:
       LOW_TIMEOUT: "0.01"