fix java-version property for publish workflow.

PiperOrigin-RevId: 422652617

Author: java-team-github-bot

.github/workflows/ci.yml

@@ -53,7 +53,7 @@ jobs:
       - name: Setup JDK
         uses: actions/setup-java@v2
         with:
-          java-version: ${{ matrix.java }}
+          java-version: 11
           distribution: 'zulu'
           server-id: google-snapshots
           server-username: MAVEN_USERNAME