fix(package): update ngx-bootstrap to version 5.1.1

Closes #152

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "font-awesome": "^4.7.0",
     "jquery": "^3.2.1",
     "ng2-charts": "^2.0.0",
-    "ngx-bootstrap": "^4.0.0",
+    "ngx-bootstrap": "^5.1.1",
     "popper.js": "^1.14.3",
     "rxjs": "~6.3.3",
     "tslib": "^1.9.0",