build(deps): bump cachix/cachix-action from 11 to 12

Bumps [cachix/cachix-action](https://github.com/cachix/cachix-action) from 11 to 12.
- [Release notes](https://github.com/cachix/cachix-action/releases)
- [Commits](cachix/cachix-action@v11...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/lint.yml

@@ -51,7 +51,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: cachix/install-nix-action@v18
-      - uses: cachix/cachix-action@v11
+      - uses: cachix/cachix-action@v12
         with:
           name: ethermint
       - uses: technote-space/get-diff-action@v6.1.1
@@ -67,7 +67,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: cachix/install-nix-action@v18
-      - uses: cachix/cachix-action@v11
+      - uses: cachix/cachix-action@v12
         with:
           name: ethermint
       - name: run gomod2nix

.github/workflows/test.yml

@@ -107,7 +107,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: cachix/install-nix-action@v18
-      - uses: cachix/cachix-action@v11
+      - uses: cachix/cachix-action@v12
         with:
           name: ethermint
           signingKey: "${{ secrets.CACHIX_SIGNING_KEY }}"
@@ -142,7 +142,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: cachix/install-nix-action@v18
-      - uses: cachix/cachix-action@v11
+      - uses: cachix/cachix-action@v12
         with:
           name: ethermint
           signingKey: "${{ secrets.CACHIX_SIGNING_KEY }}"