build(deps): bump dtolnay/rust-toolchain from 1.78.0 to 1.90.0

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from 1.78.0 to 1.90.0.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@1.78.0...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>

Author: dependabot[bot]

.github/workflows/coverage.yml

@@ -17,7 +17,7 @@ jobs:
         with:
           submodules: true
       - name: Install stable
-        uses: dtolnay/rust-toolchain@1.78.0
+        uses: dtolnay/rust-toolchain@1.90.0
         with:
           components: llvm-tools-preview
       - name: Rust cache