build(deps): bump DeterminateSystems/update-flake-lock from 14 to 15

Bumps [DeterminateSystems/update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock) from 14 to 15.
- [Release notes](https://github.com/DeterminateSystems/update-flake-lock/releases)
- [Commits](DeterminateSystems/update-flake-lock@v14...v15)

---
updated-dependencies:
- dependency-name: DeterminateSystems/update-flake-lock
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/update-flake-lock.yml

@@ -17,7 +17,7 @@ jobs:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
       - name: Update flake.lock
-        uses: DeterminateSystems/update-flake-lock@v14
+        uses: DeterminateSystems/update-flake-lock@v15
         with:
           commit-msg: "chore: update flake.lock"
           gpg-fingerprint: ${{ secrets.GPG_FINGERPRINT }}