Exclude eslint from Dependabot group updates (#34)

Because `eslint-config-stylelint` has not supported `eslint@9` yet.

.github/dependabot.yml

@@ -11,6 +11,7 @@ updates:
     groups:
       development-dependencies:
         dependency-type: 'development'
+        exclude-patterns: ['eslint']
 
   - package-ecosystem: github-actions
     directory: '/'