github actions input are strings

ref: https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#inputsinput_iddefault

Signed-off-by: Cyril Jouve <jv.cyril@gmail.com>

Author: jouve

action.yml

@@ -48,11 +48,11 @@ inputs:
   mark_as_latest:
     description: Mark the created GitHub release as 'latest'
     required: false
-    default: true
+    default: "true"
   packages_with_index:
     description: "Upload chart packages directly into publishing branch"
     required: false
-    default: false
+    default: "false"
   pages_branch:
     description: "Name of the branch to be used to push the index and artifacts. (default to: gh-pages but it is not set in the action it is a default value for the chart-releaser binary)"
     required: false