Fix newline at end of file in collection-index.yml

Author: abdurriq

_data/collection-index.yml

@@ -1545,4 +1545,4 @@
   maintainer: sjp
   contact: https://github.com/sjp/tectonic-feature/issues
   repository: https://github.com/sjp/tectonic-feature
-  ociReference: ghcr.io/sjp/tectonic-feature
+  ociReference: ghcr.io/sjp/tectonic-feature