Support custom target_commitish value (#76)

* Make target_commitish configurable

* Store compiled action for testing

* Add target_commitish to metadata

* Allow override of target_commitish for updating

* Print commit usage

* Improve message for commit usage

* Update draft releases too

* Revert "Update draft releases too"

This reverts commit ff30f8edb1.

* Integrate latest changes from upstream.

action.yml

@@ -30,6 +30,9 @@ inputs:
   repository:
     description: 'Repository to make releases against, in <owner>/<repo> format'
     required: false
+  target_commitish:
+    description: 'Commitish value that determines where the Git tag is created from. Can be any branch or commit SHA.'
+    required: false
 env:
   'GITHUB_TOKEN': 'As provided by Github Actions'
 outputs: