ci: pin udeps job to nightly-2026-05-11

cargo-udeps 0.1.61 segfaults on nightly >= 2026-05-19 due to an
incompatibility with rustc internals. Pin to the last known-good
nightly to unblock CI. A follow-up should migrate to cargo-machete
to remove the nightly fragility entirely.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: will-2012

.github/workflows/ci.yml

@@ -49,13 +49,13 @@ jobs:
         run: sudo apt-get update && sudo apt-get install -y liburing-dev pkg-config libclang-dev
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly
+          toolchain: nightly-2026-05-11
           components: rustfmt
           override: true
       - uses: Swatinem/rust-cache@v2
       - uses: taiki-e/install-action@cargo-udeps
       - name: Run cargo udeps
-        run: cargo +nightly udeps --workspace --lib --examples --tests --benches --all-features --locked
+        run: cargo +nightly-2026-05-11 udeps --workspace --lib --examples --tests --benches --all-features --locked
 
   clippy:
     name: clippy