Bump slash from 3.0.0 to 4.0.0

Bumps [slash](https://github.com/sindresorhus/slash) from 3.0.0 to 4.0.0.
- [Release notes](https://github.com/sindresorhus/slash/releases)
- [Commits](sindresorhus/slash@v3.0.0...v4.0.0)

---
updated-dependencies:
- dependency-name: slash
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -23,7 +23,7 @@
     "k-progress": "^1.5.0",
     "lodash": "^4.17.21",
     "phoenix": "^1.5.9",
-    "slash": "^3.0.0",
+    "slash": "^4.0.0",
     "validate-npm-package-name": "^3.0.0",
     "vue": "^2.6.14",
     "vue-slider-component": "^3.2.14",