fix: ReDoS vuln in [email protected] › [email protected] (#3266)

https://snyk.io/test/npm/mocha/5.0.2?severity=high&severity=medium&severity=low

Author: anishkny

package.json

@@ -309,7 +309,7 @@
     "browser-stdout": "1.3.1",
     "commander": "2.11.0",
     "debug": "3.1.0",
-    "diff": "3.3.1",
+    "diff": "3.5.0",
     "escape-string-regexp": "1.0.5",
     "glob": "7.1.2",
     "growl": "1.10.3",