chore: bump @genkit-ai/core version to @genkit-ai/core@1.4.0

Author: Automated Version Bump

js/core/package.json

@@ -7,7 +7,7 @@
     "genai",
     "generative-ai"
   ],
-  "version": "1.3.0",
+  "version": "1.4.0",
   "type": "commonjs",
   "scripts": {
     "check": "tsc",