[ci] Roll pinned nightly toolchain (#521)

Author: google-pr-creation-bot

Cargo.toml

@@ -26,7 +26,7 @@ all-features = true
 [package.metadata.ci]
 # The versions of the stable and nightly compiler toolchains to use in CI.
 pinned-stable = "1.73.0"
-pinned-nightly = "nightly-2023-10-17"
+pinned-nightly = "nightly-2023-10-18"
 
 [features]
 default = ["byteorder"]