Add check to ensure release drafter doesn't run on forks (#887)

Author: jacobtomlinson

.github/workflows/release-drafter.yml

@@ -10,6 +10,7 @@ permissions:
 
 jobs:
   update_release_draft:
+    if: github.repository == 'dask/dask-kubernetes'
     permissions:
       # Write permission is required to create a GitHub release
       contents: write

.github/workflows/release-publish.yml

@@ -10,6 +10,7 @@ permissions:
 
 jobs:
   publish_release:
+    if: github.repository == 'dask/dask-kubernetes'
     permissions:
       # Write permission is required to publish a GitHub release
       contents: write