[web-transport-quinn] Include query string in :path pseudo-header for CONNECT requests

Hey @kixelated 👋 I noticed that the current implementation of the CONNECT request omits the query component from the :path pseudo-header. According to RFC 9114 4.3.1 (HTTP/3), the :path header should include both the path and query string when applicable. This can be important for compatibility with servers or intermediaries that expect the full request target. I've opened a PR to address this: https://github.com/kixelated/web-transport-rs/pull/70 — it appends the query string (if present) to the :path value so that it more accurately reflects the full URL. Let me know what you think or if there are any concerns! Happy to adjust if needed. 😊