feat: add @rspack/core as an optional peer dependency (#1568)

Author: snitin315

package.json

@@ -43,8 +43,17 @@
     "dist"
   ],
   "peerDependencies": {
+    "@rspack/core": "0.x || 1.x",
     "webpack": "^5.0.0"
   },
+  "peerDependenciesMeta": {
+    "@rspack/core": {
+      "optional": true
+    },
+    "webpack": {
+      "optional": true
+    }
+  },
   "dependencies": {
     "icss-utils": "^5.1.0",
     "postcss": "^8.4.33",