build(deps): Update commander requirement from ~2.20.0 to ~3.0.1

Updates the requirements on [commander](https://github.com/tj/commander.js) to permit the latest version.
- [Release notes](https://github.com/tj/commander.js/releases)
- [Changelog](https://github.com/tj/commander.js/blob/master/CHANGELOG.md)
- [Commits](tj/commander.js@v2.20.0...v3.0.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

packages/core/package.json

@@ -57,7 +57,7 @@
     "@stryker-mutator/api": "^2.0.2",
     "@stryker-mutator/util": "^2.0.2",
     "chalk": "~2.4.1",
-    "commander": "~2.20.0",
+    "commander": "~3.0.1",
     "get-port": "~5.0.0",
     "glob": "~7.1.2",
     "inquirer": "~6.5.0",