fix: add swr/_internal to paths (#2105)

Author: jason89521

tsconfig.json

@@ -22,7 +22,8 @@
       "swr": ["./core/index.ts"],
       "swr/infinite": ["./infinite/index.ts"],
       "swr/immutable": ["./immutable/index.ts"],
-      "swr/mutation": ["./mutation/index.ts"]
+      "swr/mutation": ["./mutation/index.ts"],
+      "swr/_internal": ["./_internal/index.ts"]
     },
     "incremental": true
   },