chore(deps): bump DeterminateSystems/update-flake-lock from 18 to 19 (#309)

Bumps [DeterminateSystems/update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock) from 18 to 19.
- [Release notes](https://github.com/DeterminateSystems/update-flake-lock/releases)
- [Commits](https://github.com/DeterminateSystems/update-flake-lock/compare/v18...v19)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/update-flake.yml

@@ -23,7 +23,7 @@ jobs:
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - name: Update flake.lock
       id: flakeupdate
-      uses: DeterminateSystems/update-flake-lock@v18
+      uses: DeterminateSystems/update-flake-lock@v19
       with:
         token: ${{ secrets.PAT_FLAKE_UPDATE }}
         branch: "automation/flake-update"