Upgrade concourse/github-release-resource to 1.8.0

Author: philwebb

ci/pipeline.yml

@@ -128,7 +128,7 @@ resource_types:
   type: registry-image
   source:
     repository: concourse/github-release-resource
-    tag: 1.5.5
+    tag: 1.8.0
 resources:
 - name: git-repo
   type: git