ci: update dtolnay/rust-toolchain requirement to 29eef336d9b2848a0b548edc03f92a220660cdb8

Updates the requirements on [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) to permit the latest version.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](https://github.com/dtolnay/rust-toolchain/commits/29eef336d9b2848a0b548edc03f92a220660cdb8)

---
updated-dependencies:
- dependency-name: dtolnay/rust-toolchain
  dependency-version: 29eef336d9b2848a0b548edc03f92a220660cdb8
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
       contents: read
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # actions/checkout v6
-      - uses: dtolnay/rust-toolchain@5b842231ba77f5c045dba54ac5560fed2db780e2 # dtolnay/rust-toolchain nightly
+      - uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # dtolnay/rust-toolchain nightly
         with:
           components: rustfmt
       - run: cargo +nightly fmt --all -- --check
@@ -66,7 +66,7 @@ jobs:
             rust: "1.85"  # MSRV
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # actions/checkout v6
-      - uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # dtolnay/rust-toolchain master
+      - uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # dtolnay/rust-toolchain master
         with:
           toolchain: ${{ matrix.rust }}
       - uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # Swatinem/rust-cache v2