[ci] Roll pinned stable toolchain (#3069)

Author: google-pr-creation-bot

Cargo.toml

@@ -84,7 +84,7 @@ no-zerocopy-panic-in-const-and-vec-try-reserve-1-57-0 = "1.57.0"
 
 [package.metadata.ci]
 # The versions of the stable and nightly compiler toolchains to use in CI.
-pinned-stable = "1.93.0"
+pinned-stable = "1.93.1"
 pinned-nightly = "nightly-2026-01-25"
 
 [package.metadata.docs.rs]