switch to new environment variable syntax (#181)

Author: gabrielittner

.github/workflows/publish-snapshot.yml

@@ -21,7 +21,7 @@ jobs:
 
  - name: Retrieve version
  run: |
- echo ::set-env name=VERSION_NAME::$(cat gradle.properties | grep -w "VERSION_NAME" | cut -d'=' -f2)
+ echo "VERSION_NAME=$(cat gradle.properties | grep -w "VERSION_NAME" | cut -d'=' -f2)" >> $GITHUB_ENV
 
  - name: Publish snapshot
  run: ./gradlew uploadArchives --no-daemon --no-parallel