Bump the actions group across 1 directory with 3 updates

Bumps the actions group with 3 updates in the / directory: [taiki-e/install-action](https://github.com/taiki-e/install-action), [dependabot/fetch-metadata](https://github.com/dependabot/fetch-metadata) and [cachix/install-nix-action](https://github.com/cachix/install-nix-action).


Updates `taiki-e/install-action` from 2.68.34 to 2.70.2
- [Release notes](https://github.com/taiki-e/install-action/releases)
- [Changelog](https://github.com/taiki-e/install-action/blob/main/CHANGELOG.md)
- [Commits](de6bbd1333...e9e8e031bc)

Updates `dependabot/fetch-metadata` from 2.5.0 to 3.0.0
- [Release notes](https://github.com/dependabot/fetch-metadata/releases)
- [Commits](21025c705c...ffa630c65f)

Updates `cachix/install-nix-action` from 31.10.1 to 31.10.3
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Changelog](https://github.com/cachix/install-nix-action/blob/master/RELEASE.md)
- [Commits](1ca7d21a94...96951a368b)

---
updated-dependencies:
- dependency-name: taiki-e/install-action
  dependency-version: 2.70.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: actions
- dependency-name: dependabot/fetch-metadata
  dependency-version: 3.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: cachix/install-nix-action
  dependency-version: 31.10.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
...

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

.github/workflows/coverage.yml

@@ -25,7 +25,7 @@ jobs:
 
       - run: rustup toolchain install stable --profile minimal --component llvm-tools-preview --no-self-update
 
-      - uses: taiki-e/install-action@de6bbd1333b8f331563d54a051e542c7dfef81c3 # v2.68.34
+      - uses: taiki-e/install-action@e9e8e031bcd90cdbe8ac6bb1d376f8596e587fbf # v2.70.2
         with:
           tool: cargo-llvm-cov