CI: Remove pyzmq from ADAPTERS

Author: mrkn

.github/workflows/ci.yml

@@ -74,7 +74,7 @@ jobs:
     - name: Run tests
       env:
         PYTHON: python3
-        ADAPTERS: cztop ffi-rzmq pyzmq
+        ADAPTERS: cztop ffi-rzmq
       run: |
         for adapter in $ADAPTERS; do
           export IRUBY_TEST_SESSION_ADAPTER_NAME=$adapter