Update shakapacker config to enable HMR

config/shakapacker.yml

@@ -70,7 +70,7 @@ development:
     port: 3035
     # Hot Module Replacement updates modules while the application is running without a full reload
     # Used instead of the `hot` key in https://webpack.js.org/configuration/dev-server/#devserverhot
-    hmr: false
+    hmr: true
     # If HMR is on, CSS will by inlined by delivering it as part of the script payload via style-loader. Be sure
     # that you add style-loader to your project dependencies.
     #
@@ -92,7 +92,7 @@ development:
     # Should we use gzip compression?
     compress: true
     # Note that apps that do not check the host are vulnerable to DNS rebinding attacks
-    allowed_hosts: 'auto'
+    allowed_hosts: 'all'
     # Shows progress and colorizes output of bin/shakapacker[-dev-server]
     pretty: true
     headers: