Update dependency rimraf to v6

Author: renovate[bot]

package.json

@@ -50,7 +50,7 @@
     "mocha": "~6.1.4",
     "mocha-lcov-reporter": "1.3.0",
     "multiline": "1.0.2",
-    "rimraf": "2.6.3",
+    "rimraf": "6.0.0",
     "sinon": "^7.3.2",
     "standard": "6.0.8"
   },