Fix java version unset.

.github/workflows/docker-build.yml

@@ -23,10 +23,10 @@ jobs:
       - uses: actions/checkout@v3
       - name: Create Version File
         run: echo $(git log -1 --date=short --pretty=format:%cd)-$(git rev-parse --short HEAD) > VERSION
-      - name: set up JDK ${{ matrix.java }}
+      - name: set up JDK 17
         uses: actions/setup-java@v3
         with:
-          java-version: ${{ matrix.java }}
+          java-version: 17
           distribution: temurin
           check-latest: true
           cache: "gradle"