build: add rust-toolchain.toml file

.github/workflows/ci.yaml

@@ -55,7 +55,7 @@ jobs:
       # Here we use the latest stable Rust toolchain already installed by GitHub
       # Ideally we should run it for every target, but we cannot rely on unstable toolchains
       # due to Clippy not being consistent between them.
-      - run: cargo clippy --workspace --exclude libc-test --exclude ctest-test --all-targets -- -D warnings
+      - run: cargo +stable clippy --workspace --exclude libc-test --exclude ctest-test --all-targets -- -D warnings
 
   # This runs `cargo build --target ...` for all T1 and T2 targets`
   verify_build:

ci/install-rust.sh

@@ -26,6 +26,7 @@ fi
 rustup set profile minimal
 rustup update --force "$toolchain" --no-self-update
 rustup default "$toolchain"
+rustup override set "$toolchain"
 
 if [ -n "${TARGET:-}" ]; then
     echo "Install target"

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "nightly"