Update title and date for RTN post

Author: traviscross

posts/inside-rust/2024-09-23-rtn-call-for-testing.md renamed to posts/inside-rust/2024-09-26-rtn-call-for-testing.md

@@ -1,6 +1,6 @@
 ---
 layout: post
-title: "Return Type Notation MVP: Call for Testing!"
+title: "Return type notation MVP: Call for testing!"
 author: Michael Goulet
 team: The Async Working Group <https://www.rust-lang.org/governance/wgs/wg-async>
 ---