feat: allow specifying a path to flake.nix within the repository

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 16 to 17.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v16...v17)

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

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

.github/workflows/ci.yml

@@ -12,6 +12,6 @@ jobs:
         with:
           fetch-depth: 0
       - name: Install Nix
-        uses: cachix/install-nix-action@v16
+        uses: cachix/install-nix-action@v17
       - name: Shellcheck
         run: nix-shell --run 'shellcheck $(find . -type f -name "*.sh" -executable)'

.github/workflows/update.yml

@@ -11,7 +11,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
       - name: Install Nix
-        uses: cachix/install-nix-action@v16
+        uses: cachix/install-nix-action@v17
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}

README.md

@@ -122,6 +122,7 @@ jobs:
         uses: DeterminateSystems/update-flake-lock@vX
         with:
           inputs: input1 input2 input3
+          path-to-flake-dir: 'nix/' # in this example our flake doesn't sit at the root of the repository, it sits under 'nix/flake.nix'
 ```
 
 ## Running GitHub Actions CI

action.yml

@@ -17,6 +17,10 @@ inputs:
     description: 'The branch of the PR to be created'
     required: false
     default: "update_flake_lock_action"
+  path-to-flake-dir:
+    description: 'The path of the directory containing `flake.nix` file within your repository. Useful when `flake.nix` cannot reside at the root of your repository.'
+    required: false
+    default: ''
   pr-title:
     description: 'The title of the PR to be created'
     required: false
@@ -114,6 +118,7 @@ runs:
         GIT_COMMITTER_EMAIL: ${{ env.GIT_COMMITTER_EMAIL }}
         TARGETS: ${{ inputs.inputs }}
         COMMIT_MSG: ${{ inputs.commit-msg }}
+        PATH_TO_FLAKE_DIR: ${{ inputs.path-to-flake-dir }}
     - name: Save PR Body as file
       uses: DamianReeves/write-file-action@v1.1
       with:

update-flake-lock.sh

@@ -1,6 +1,10 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+if [[ -n "$PATH_TO_FLAKE_DIR" ]]; then
+  cd "$PATH_TO_FLAKE_DIR"
+fi
+
 if [[ -n "$TARGETS" ]]; then
     inputs=()
     for input in $TARGETS; do