chore(deps): bump cachix/install-nix-action from 27 to 31

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 27 to 31.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Changelog](https://github.com/cachix/install-nix-action/blob/master/RELEASE.md)
- [Commits](cachix/install-nix-action@v27...v31)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-version: '31'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/cli.yml

@@ -54,7 +54,7 @@ jobs:
         with:
           go-version-file: go.mod
 
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-25.11
           extra_nix_config: |

.github/workflows/integration-test.yml

@@ -23,7 +23,7 @@ jobs:
           sudo modprobe vsock_loopback
           test -e /dev/vsock
 
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-25.11
           extra_nix_config: |

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
           ref: master
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@v27
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-25.11
           extra_nix_config: |