Fix the import for the app to compile

Workaround for the latest CLI bug angular/angular-cli#9185

Author: punisherx

src/styles.css

@@ -1,5 +1,5 @@
 /* You can add global styles to this file, and also import other style files */
-@import '~@angular/material/prebuilt-themes/indigo-pink.css';
+@import '@angular/material/prebuilt-themes/indigo-pink.css';
 
 html, body {
   padding: 0;