Fix casing of OpenZedUrl action (#7045)

This PR updates the casing of the `OpenZedUrl` action to match the [Rust
naming
guidelines](https://rust-lang.github.io/api-guidelines/naming.html).

Release Notes:

- N/A

crates/zed_actions/src/lib.rs

@@ -16,10 +16,10 @@ pub struct OpenBrowser {
 }
 
 #[derive(Clone, PartialEq, Deserialize)]
-pub struct OpenZedURL {
+pub struct OpenZedUrl {
     pub url: String,
 }
 
-impl_actions!(zed, [OpenBrowser, OpenZedURL]);
+impl_actions!(zed, [OpenBrowser, OpenZedUrl]);
 
 actions!(zed, [OpenSettings, Quit]);