Bump shelljs from 0.7.8 to 0.8.5

Bumps [shelljs](https://github.com/shelljs/shelljs) from 0.7.8 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@v0.7.8...v0.8.5)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -59,7 +59,7 @@
     "postcss-flexbugs-fixes": "^2.1.0",
     "sass": "^1.13.0",
     "sass-inline-svg": "^1.2.3",
-    "shelljs": "^0.7.5",
+    "shelljs": "^0.8.5",
     "shx": "^0.2.1",
     "svgo": "^1.3.2",
     "time-grunt": "^1.4.0",