Bump shelljs from 0.8.3 to 0.8.5 in /scripts/firepit-builder (#4018)

Bumps [shelljs](https://github.com/shelljs/shelljs) from 0.8.3 to 0.8.5.
- [Release notes](https://github.com/shelljs/shelljs/releases)
- [Changelog](https://github.com/shelljs/shelljs/blob/master/CHANGELOG.md)
- [Commits](shelljs/shelljs@v0.8.3...v0.8.5)

---
updated-dependencies:
- dependency-name: shelljs
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

scripts/firepit-builder/package.json

@@ -11,7 +11,7 @@
   "license": "MIT",
   "private": true,
   "dependencies": {
-    "shelljs": "^0.8.3",
+    "shelljs": "^0.8.5",
     "yargs": "^13.3.0"
   }
 }