ci: Stop fetching Scylla RC releases for CI tests

Change CI version fetcher to pull only released versions as
the RC releases may be unstable to be tested with.
These releases should be tested as part of driver-matrix tests
of those release cycle.

Fixes: #290

Author: roydahan

.github/workflows/[email protected]

@@ -104,7 +104,7 @@ jobs:
         id: fetch-versions
         run: |
           pip3 install -r ci/requirements.txt
-          echo "scylla-integration-tests-versions=$(python3 ci/version_fetch.py scylla-oss-stable:2 scylla-oss-rc scylla-enterprise-stable:2 scylla-enterprise-rc)" >> $GITHUB_OUTPUT
+          echo "scylla-integration-tests-versions=$(python3 ci/version_fetch.py scylla-oss-stable:2 scylla-enterprise-stable:2 scylla-enterprise-rc)" >> $GITHUB_OUTPUT
           echo "cassandra-integration-tests-versions=$(python3 ci/version_fetch.py cassandra3-stable:1)" >> $GITHUB_OUTPUT
 
     outputs: