fix: include fixtures/ in published package

Author: NathanFlurry

packages/core/package.json

@@ -6,7 +6,8 @@
 	"main": "./dist/index.js",
 	"types": "./dist/index.d.ts",
 	"files": [
-		"dist"
+		"dist",
+		"fixtures"
 	],
 	"exports": {
 		".": {