CodeQL: setup JDK for build

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

.github/workflows/codeql-analysis.yml

@@ -46,6 +46,11 @@ jobs:
       with:
         languages: ${{ matrix.language }}
 
+    -   name: Set up JDK 11
+        uses: actions/setup-java@v2
+        with:
+            distribution: "adopt"
+            java-version: 11
     - name: Assemble
       run: |
         mkdir -p $HOME/.gradle