fix(deps): require use-sync-external-store ^1.5.0 so the ESM build loads in Node

dist/index.js imports `use-sync-external-store/shim`, which is kept
external. Before 1.5.0 the package had no `exports` map, so Node's ESM
resolver treats `/shim` as a directory and throws
ERR_UNSUPPORTED_DIR_IMPORT. That breaks anything that loads the ESM build
without a bundler: Vitest tests in apps that use reactfire, SSR that keeps
dependencies external, and plain Node scripts. The CJS build is fine.

Raise the floor to ^1.5.0 (lockfile: 1.2.0 -> 1.7.0).

Author: jhuleatt

package-lock.json

@@ -109,7 +109,7 @@
   "dependencies": {
     "rxfire": "^6.1.0",
     "rxjs": "^6.6.3 || ^7.0.1",
-    "use-sync-external-store": "^1.2.0"
+    "use-sync-external-store": "^1.5.0"
   },
   "allowScripts": {
     "@firebase/util@1.12.1": true,