add github actions publish workflow step

Author: fgrutsch

.github/workflows/ci.yml

@@ -45,3 +45,37 @@ jobs:
         uses: codecov/codecov-action@v1
         with:
           fail_ci_if_error: true
+
+  publish:
+    name: Publish
+    needs: [build]
+    if: github.event_name != 'pull_request' && (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/v'))
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      
+      - name: Setup Scala
+        uses: olafurpg/setup-scala@v10
+        with:
+          java-version: "[email protected]"
+
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ~/.sbt
+            ~/.ivy2/cache
+            ~/.coursier/cache/v1
+            ~/.cache/coursier/v1          
+          key: |
+            ${{ runner.os }}-sbt-${{ hashFiles('project/build.properties') }}-${{ hashFiles('**/*.sbt') }}
+
+      - name: Publish artifacts
+        env:
+          PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
+          PGP_SECRET: ${{ secrets.PGP_SECRET }}
+          SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
+          SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
+        run: sbt ci-release