fix(package): update ngx-markdown to version 8.1.2

Closes #98

Author: greenkeeper[bot]

demo/package.json

@@ -46,7 +46,7 @@
     "bootstrap": "^4.2.1",
     "core-js": "^2.6.2",
     "font-awesome": "^4.7.0",
-    "ngx-markdown": "^7.0.4",
+    "ngx-markdown": "^8.1.2",
     "rxjs": "^6.3.3",
     "zone.js": "^0.8.26"
   },