build: switch back to jdk 12 due to errors with nexus-staging-maven-plugin

Author: McFoggy

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v2
         with:
-          java-version: '17'
+          java-version: '12'
           distribution: 'adopt'
           cache: maven
 

.github/workflows/deploy.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v2
         with:
-          java-version: '17'
+          java-version: '12'
           distribution: 'adopt'
           cache: maven