Bump grunt-shell from 3.0.1 to 4.0.0

Bumps [grunt-shell](https://github.com/sindresorhus/grunt-shell) from 3.0.1 to 4.0.0.
- [Release notes](https://github.com/sindresorhus/grunt-shell/releases)
- [Commits](sindresorhus/grunt-shell@v3.0.1...v4.0.0)

---
updated-dependencies:
- dependency-name: grunt-shell
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package-lock.json

@@ -47,7 +47,7 @@
     "codecov": "^3.6.5",
     "grunt": "^1.1.0",
     "grunt-jsdoc": "^2.4.1",
-    "grunt-shell": "^3.0.1",
+    "grunt-shell": "^4.0.0",
     "ink-docstrap": "^1.3.2",
     "jsdoc": "^4.0.2",
     "mktemp": "^1.0.0",