build(deps): bump dtolnay/rust-toolchain from 1.73.0 to 1.100.0

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from 1.73.0 to 1.100.0.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@1.73.0...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/test.yaml

@@ -394,7 +394,7 @@ jobs:
           persist-credentials: false
 
       - name: Install rust toolchain
-        uses: dtolnay/rust-toolchain@1.73.0
+        uses: dtolnay/rust-toolchain@1.100.0
 
       - name: Test MSRV
         run: cargo check --manifest-path librustls/Cargo.toml --locked --lib --features=aws-lc-rs