chore(deps): bump cachix/install-nix-action from 30 to 31

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 30 to 31.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@v30...v31)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
         solc-select use 0.5.7 --always-install
     - name: Set up nix
       if: matrix.type == 'dapp'
-      uses: cachix/install-nix-action@v30
+      uses: cachix/install-nix-action@v31
     - name: Set up cachix
       if: matrix.type == 'dapp'
       uses: cachix/cachix-action@v15