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)

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

Author: dependabot[bot]

package-lock.json

@@ -10,7 +10,7 @@
     "graceful-fs": "^4.2.4"
   },
   "devDependencies": {
-    "bootstrap": "^3.3.7",
+    "bootstrap": "^3.4.1",
     "browser-sync": "^2.26.7",
     "del": "^3.0.0",
     "extensions": "edsilv/extensions",