Update publish to Java 11

Author: abnegate

.github/workflows/publish.yml

@@ -12,10 +12,10 @@ jobs:
     steps:
       - name: Check out code
         uses: actions/checkout@v2
-      - name: Set up JDK 1.8
+      - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:
-          java-version: 1.8
+          java-version: 11
         # Base64 decodes and pipes the GPG key content into the secret file
       - name: Prepare environment
         env: