Bump cachix/install-nix-action in the github-actions group

Bumps the github-actions group with 1 update: [cachix/install-nix-action](https://github.com/cachix/install-nix-action).


Updates `cachix/install-nix-action` from V28 to 29
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@V28...v29)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  dependency-group: github-actions
...

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

.github/workflows/nix_update.yml

@@ -12,7 +12,7 @@ jobs:
       pull-requests: write
     steps:
       - uses: actions/[email protected]
-      - uses: cachix/install-nix-action@V28
+      - uses: cachix/install-nix-action@v29
       - uses: fregante/setup-git-user@v2
       - run: nix flake update --commit-lock-file
       - run: nix flake check .

.github/workflows/regenerate-go-sri.yml

@@ -37,7 +37,7 @@ jobs:
         with:
           token: ${{secrets.REPO_CONTENT_UPDATE_TOKEN}}
           fetch-depth: 0 # otherwise, you will failed to push refs to dest repo
-      - uses: cachix/install-nix-action@V28
+      - uses: cachix/install-nix-action@v29
       - uses: DeterminateSystems/magic-nix-cache-action@v8
       - name: re-generate SRI
         run: "nix --extra-experimental-features nix-command --extra-experimental-features flakes run .#generate-sri-default"