Upgrade CI to publish to Maven Central directly

Closes gh-1199

ci/tasks/generate-changelog.yml

@@ -4,10 +4,10 @@ image_resource:
   type: registry-image
   source:
     repository: springio/github-changelog-generator
-    tag: '0.0.5'
+    tag: '0.0.6'
 inputs:
   - name: git-repo
-  - name: version
+  - name: artifactory-repo
 outputs:
   - name: generated-changelog
 params: