Bump DeterminateSystems/update-flake-lock from 17 to 19

Author: rszamszur

template/{% if github_actions %}.github{% endif %}/workflows/{% if nix %}update-flake.yml{% endif %}.jinja

@@ -15,7 +15,7 @@ jobs:
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v4
       - name: Update flake.lock
-        uses: DeterminateSystems/update-flake-lock@v17
+        uses: DeterminateSystems/update-flake-lock@v19
         with:
           pr-title: "Update flake.lock"
           # https://github.com/DeterminateSystems/update-flake-lock#with-a-personal-authentication-token