Update minimist to a non-vulnerable version.

[lgarron]

• This addresses an npm audit vulnerability alert for projects using workbox, which in turn depends on minimist@1.2.5: GHSA-xvch-5gv4-984h

Prior to creating a pull request, please follow all the steps in the contributing guide.

R: @jeffposnick @tropicadri

[lgarron]

Note: npm audit still warns about quite a few vulns with workbox dev dependencies:

node_modules/gulp/node_modules/y18n
node_modules/y18n

66 vulnerabilities (13 moderate, 52 high, 1 critical)

To address issues that do not require attention, run:
  npm audit fix

To address all issues (including breaking changes), run:
  npm audit fix --force

[lgarron]

Thanks!
I'd appreciate a release soon so I can update workbox in my dependencies without hacks. :-D