Use fork of grunt-shell.

[mattcollier]

PR for grunt-shell submitted upstream. Hopefully it will be accepted in short order.

sindresorhus/grunt-shell#125

This is to address this:

                       === npm audit security report ===                        
                                                                                
┌──────────────────────────────────────────────────────────────────────────────┐
│                                Manual Review                                 │
│            Some vulnerabilities require your attention to resolve            │
│                                                                              │
│         Visit https://go.npm.me/audit-guide for additional guidance          │
└──────────────────────────────────────────────────────────────────────────────┘
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ Moderate      │  Inefficient Regular Expression Complexity in                │
│               │ chalk/ansi-regex                                             │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ ansi-regex                                                   │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Patched in    │ >=5.0.1                                                      │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ grunt-shell                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ grunt-shell > strip-ansi > ansi-regex                        │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://github.com/advisories/GHSA-93q8-gq69-wqmw            │
└───────────────┴──────────────────────────────────────────────────────────────┘
found 1 moderate severity vulnerability in 299 scanned packages
  1 vulnerability requires manual review. See the full report for details.

[davidlehn]

No longer using grunt tooling. Closing.