Update compiler version dependency

This is necessary for this package's tests and sass-spec's to use Dart
Sass from head.

Author: nex3

package.json

@@ -2,7 +2,7 @@
   "name": "sass-embedded",
   "version": "1.56.2",
   "protocol-version": "1.1.0",
-  "compiler-version": "1.56.2",
+  "compiler-version": "1.56.3-dev",
   "description": "Node.js library that communicates with Embedded Dart Sass using the Embedded Sass protocol",
   "repository": "sass/embedded-host-node",
   "author": "Google Inc.",