Update cookie_store requirement from 0.20 to 0.21

Updates the requirements on [cookie_store](https://github.com/pfernie/cookie_store) to permit the latest version.
- [Changelog](https://github.com/pfernie/cookie_store/blob/master/CHANGELOG.md)
- [Commits](pfernie/cookie_store@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: cookie_store
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

squire_sdk/Cargo.toml

@@ -54,7 +54,7 @@ serde_json = { version = "1.0.108", optional = true }
 postcard = { version = "1.0", features = ["alloc"], optional = true }
 
 # Client deps
-cookie_store = { version = "0.20", optional = true }
+cookie_store = { version = "0.21", optional = true }
 
 # Server deps
 axum = { version = "0.7.2", features = ["ws", "json", "macros"], optional = true }