feat: add support for configuring diff.relative (#515)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

action.yml

@@ -70,6 +70,9 @@ inputs:
     description: 'Output filenames completely verbatim by setting this to false'
     default: 'true'
     required: false
+  diff_relative:
+    description: 'Exclude changes outside the current directory and show pathnames relative to it'
+    required: false
 
 outputs:
   added_files:
@@ -203,6 +206,7 @@ runs:
         INPUT_INCLUDE_ALL_OLD_NEW_RENAMED_FILES: ${{ inputs.include_all_old_new_renamed_files }}
         INPUT_OLD_NEW_SEPARATOR: ${{ inputs.old_new_separator }}
         INPUT_OLD_NEW_FILES_SEPARATOR: ${{ inputs.old_new_files_separator }}
+        INPUT_DIFF_RELATIVE: ${{ inputs.diff_relative }}
 
 branding:
   icon: file-text