chore: drop unused mkdirp dependency

Author: nikku

package-lock.json

@@ -39,7 +39,6 @@
     "eslint-plugin-bpmn-io": "^1.0.1",
     "eslint-plugin-import": "^2.8.0",
     "esm": "^3.0.25",
-    "mkdirp": "^0.5.1",
     "mocha": "^10.7.0",
     "npm-run-all2": "^6.2.2"
   },