feat: support new remote branch creation (#329)

* fix: don't pull on new branch creation

* fix: don't show useless errors on branch creation

* feat: add branch_mode input

* fix: properly exit after fialed input check

* docs(README): document new input

action.yml

@@ -15,6 +15,10 @@ inputs:
   branch:
     description: Name of the branch to use, if different from the one that triggered the workflow
     required: false
+  branch_mode:
+    description: How the action should behave when the targeted branch is missing
+    required: false
+    default: throw
   committer_name:
     description: The name of the custom committer you want to use
     required: false