Update toolchain to 08-25-2025 (#4316)

This PR updates Rust toolchain to 08/25/2025

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

Author: thanhnguyen-aws

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2025-08-20"
+channel = "nightly-2025-08-25"
 components = ["llvm-tools", "rustc-dev", "rust-src", "rustfmt"]

tests/ui/derive-arbitrary/non_arbitrary_field/expected

@@ -1,4 +1,6 @@
 error[E0277]: the trait bound `NotArbitrary: kani::Arbitrary` is not satisfied
 |\
 |     not_arbitrary: NotArbitrary,\
-|     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `kani::Arbitrary` is not implemented for `NotArbitrary`
+|     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
+
+help: the trait `kani::Arbitrary` is not implemented for `NotArbitrary`

tests/ui/derive-arbitrary/non_arbitrary_param/expected

@@ -1,4 +1,6 @@
 error[E0277]: the trait bound `Void: kani::Arbitrary` is not satisfied
 |\
 |     let _wrapper: Wrapper<Void> = kani::any();\
-|                                   ^^^^^^^^^^^ the trait `kani::Arbitrary` is not implemented for `Void`
+|                                   ^^^^^^^^^^^ unsatisfied trait bound
+
+help: the trait `kani::Arbitrary` is not implemented for `Void`