Bump bootstrap from 3.3.7 to 3.4.1

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 3.3.7 to 3.4.1.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](twbs/bootstrap@v3.3.7...v3.4.1)

Author: dependabot[bot]

package-lock.json

@@ -11,7 +11,7 @@
   },
   "devDependencies": {
     "axios": "^0.18",
-    "bootstrap": "^3.3.7",
+    "bootstrap": "^3.4.1",
     "popper.js": "^1.12",
     "cross-env": "^5.1",
     "laravel-mix": "^2.0",