Remove rmDir references

`rmDir` is not available on the node version used by the actions runner.

Instead, use the `del` package. It is safe, well-tested, and
cross-platform.

package.json

@@ -34,6 +34,7 @@
     "@octokit/types": "^6.21.1",
     "commander": "^8.1.0",
     "console-log-level": "^1.4.1",
+    "del": "^6.0.0",
     "fast-deep-equal": "^3.1.3",
     "file-url": "^3.0.0",
     "fs": "0.0.1-security",
@@ -54,10 +55,11 @@
   ],
   "devDependencies": {
     "@ava/typescript": "2.0.0",
+    "@types/del": "^4.0.0",
     "@types/jszip": "^3.4.1",
     "@types/long": "4.0.1",
     "@types/nock": "^11.1.0",
-    "@types/node": "^16.4.6",
+    "@types/node": "12.12",
     "@types/semver": "^7.3.8",
     "@types/sinon": "^10.0.2",
     "@typescript-eslint/parser": "^5.0.0",