fix!: add input defaults

Breaking change: token is now retrieved regardless of what the user enters.
This should cause no issues, but it's better if it goes as a major bump

Author: EndBug

action.yml

@@ -6,9 +6,11 @@ inputs:
   diff-search:
     description: Whether to search the bump commit using diffs (recommended ONLY if not using standard 'npm version' commits)
     required: false
+    default: 'false'
   file-name:
     description: A custom path to the package.json file
     required: false
+    default: 'package.json'
   file-url:
     description: A URL to use to fetch the package file, instead of loading the local file
     required: false
@@ -21,6 +23,7 @@ inputs:
   token:
     description: A GitHub token to use when running on private repos
     required: false
+    default: ${{ github.token }}
 
 outputs:
   changed: