[deps]: Update Rust to v2025-09-21

renovate[bot] · web-flow · commit 8f9769833879 · 2025-09-21T02:34:16.000Z
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
@@ -5,4 +5,4 @@ profile = "minimal"
 
 # The following is not part of the rust-toolchain.toml format,
 # but is used by our Renovate config to manage nightly versions.
-nightly-channel = "nightly-2025-08-18"
+nightly-channel = "nightly-2025-09-21"
