Fix profiling with tracy. (#5988)

The profiling APIs require a `&str`, but since the label here
is now an `Option<String>`, we must get a `&str` from it.

CHANGELOG.md

@@ -39,6 +39,12 @@ Bottom level categories:
 
 ## Unreleased
 
+### Bug Fixes
+
+#### General
+
+- Fix profiling with `tracy`. By @waywardmonkeys in [#5988](https://github.com/gfx-rs/wgpu/pull/5988)
+
 ## 22.0.0 (2024-07-17)
 
 ### Overview

wgpu-core/src/command/render.rs

@@ -1566,7 +1566,7 @@ impl Global {
 
         profiling::scope!(
             "CommandEncoder::run_render_pass {}",
-            base.label.unwrap_or("")
+            base.label.as_deref().unwrap_or("")
         );
 
         let Some(cmd_buf) = pass.parent.as_ref() else {