ci: bump dtolnay/rust-toolchain from 1.81.0 to 1.100.0

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from 1.81.0 to 1.100.0.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@1.81.0...1.100.0)

---
updated-dependencies:
- dependency-name: dtolnay/rust-toolchain
  dependency-version: 1.100.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -55,7 +55,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.81.0
+      - uses: dtolnay/rust-toolchain@1.100.0
       - run: cargo build --all-features
 
   conformance: