chore(package): make peer deps optional + add Preact

Author: David Bailey

package.json

@@ -64,8 +64,9 @@
     "rollup-plugin-uglify": "^6.0.2",
     "standard-version": "^6.0.1"
   },
-  "peerDependencies": {
-    "react": "^0.14 || ^15 || ^16"
+  "optionalPeerDependencies": {
+    "react": "^0.14 || ^15 || ^16",
+    "preact": "^8 || ^10"
   },
   "files": [
     "/dist",