Avoid unresolved vulnerability in "inflight" via glob 7

Hi,

While using grunt@1.6.1, we ran a snyk test and found security vulnerabilities.

```
✗ Medium severity vulnerability found in inflight
Description: Missing Release of Resource after Effective Lifetime
Info: https://security.snyk.io/vuln/SNYK-JS-INFLIGHT-6095116
Introduced through: glob@7.1.7
From: glob@7.1.7 > inflight@1.0.6
```

Thanks for developing grunt!

Start by inspecting the repository's dependency manifests to trace how glob@7.1.7 and inflight@1.0.6 enter grunt@1.6.1, then run the reported Snyk check. Done means the dependency path no longer introduces the cited SNYK-JS-INFLIGHT-6095116 vulnerability without breaking the existing dependency setup.

Written by the indexing model from the issue text.