Automatic toolchain upgrade to nightly-2025-10-02 (model-checking#4391)

Update Rust toolchain from nightly-2025-10-01 to nightly-2025-10-02
without any other source changes.

---------

Co-authored-by: Michael Tautschnig <[email protected]>
Co-authored-by: tautschnig <[email protected]>

Author: github-actions[bot]

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2025-10-01"
+channel = "nightly-2025-10-02"
 components = ["llvm-tools", "rustc-dev", "rust-src", "rustfmt"]

scripts/toolchain_update.sh

@@ -26,7 +26,7 @@ echo "- next: ${next_toolchain_date}"
 echo "---------------------------"
 
 if gh issue list -S \
-  "Toolchain upgrade to nightly-$next_toolchain_date failed" \
+  "\"Toolchain upgrade to nightly-$next_toolchain_date failed\"" \
   --json number,title | grep title
 then
   echo "Skip update: Found existing issue"