fix(package): update bootstrap to version 4.3.0

Closes #14

Author: greenkeeper[bot]

package.json

@@ -25,7 +25,7 @@
     "core-js": "^2.4.1",
     "rxjs": "^5.5.6",
     "zone.js": "^0.8.19",
-    "bootstrap": "4.0.0"
+    "bootstrap": "4.3.0"
   },
   "devDependencies": {
     "@angular/cli": "~1.7.1",