Bump dtolnay/rust-toolchain from 1.74.0 to 1.90.0 in /.github/workflows

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from 1.74.0 to 1.90.0.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@1.74.0...1.90.0)

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

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

.github/workflows/ci.yml

@@ -23,6 +23,6 @@ jobs:
       - uses: dtolnay/rust-toolchain@nightly
       - name: Generate minimal-version dependencies
         run: cargo -Zminimal-versions generate-lockfile
-      - uses: dtolnay/rust-toolchain@1.74.0
+      - uses: dtolnay/rust-toolchain@1.90.0
       - name: Cargo check
         run: cargo check --workspace --all-targets