Enable artifact signing

- Add secrets to ci workflow which will enable
  signing task.
- Relates #165

Author: jvalkeal

.github/workflows/ci.yml

@@ -48,6 +48,8 @@ jobs:
           java-version: 17
       - name: Build
         env:
+          ORG_GRADLE_PROJECT_signingKey: ${{ secrets.GPG_PRIVATE_KEY }}
+          ORG_GRADLE_PROJECT_signingPassword: ${{ secrets.GPG_PASSPHRASE }}
           ARTIFACTORY_USERNAME: ${{ secrets.ARTIFACTORY_USERNAME }}
           ARTIFACTORY_PASSWORD: ${{ secrets.ARTIFACTORY_PASSWORD }}
         run: |