Bump cachix/cachix-action from 10 to 12

Bumps [cachix/cachix-action](https://github.com/cachix/cachix-action) from 10 to 12.
- [Release notes](https://github.com/cachix/cachix-action/releases)
- [Commits](https://github.com/cachix/cachix-action/compare/v10...v12)

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

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

.github/workflows/ci.yml

@@ -70,7 +70,7 @@ jobs:
 
       - name: Set up cachix
         if: matrix.type == 'dapp'
-        uses: cachix/cachix-action@v10
+        uses: cachix/cachix-action@v12
         with:
           name: dapp