fix(package): update @angular/material to version 9.2.4

Closes #83

Author: greenkeeper[bot]

demo/package.json

@@ -34,7 +34,7 @@
     "@angular/flex-layout": "^7.0.0-beta.21",
     "@angular/forms": "^7.2.0",
     "@angular/http": "^7.2.0",
-    "@angular/material": "^7.2.1",
+    "@angular/material": "^9.2.4",
     "@angular/platform-browser": "^7.2.0",
     "@angular/platform-browser-dynamic": "^7.2.0",
     "@angular/platform-server": "^7.2.0",