Make Cargo-minimal and Cargo-recent lockfiles follow expected convention

.github/CONTRIBUTING.md

@@ -77,7 +77,6 @@ if [ -n "$changed_tomls" ]; then
     ./contrib/update-lock-files.sh
     stale_locks=$(git diff --name-only -- Cargo-minimal.lock Cargo-recent.lock)
     if [ -n "$stale_locks" ]; then
-        git checkout -- Cargo-minimal.lock Cargo-recent.lock
         echo "pre-commit: Cargo.toml changed and lockfiles are stale!"
         echo "Stale lockfiles:"
         echo "$stale_locks"

.github/workflows/lock-maintenance.yml

@@ -0,0 +1,25 @@
+name: Cargo lock maintenance
+on:
+  schedule:
+    - cron: "0 20 * * 0" # weekly at 20:00 UTC
+  workflow_dispatch:
+
+jobs:
+  update-lock-files:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: UPDATE_DEPS=true bash contrib/update-lock-files.sh
+      - uses: peter-evans/create-pull-request@v7
+        with:
+          token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}
+          commit-message: "chore: update Cargo lock files"
+          title: "chore: update Cargo lock files"
+          branch: chore/cargo-lock-update
+          add-paths: |
+            Cargo-minimal.lock
+            Cargo-recent.lock

.github/workflows/rust.yml

@@ -40,20 +40,6 @@ jobs:
       - name: Run tests
         run: RUST_LOG=debug bash contrib/test.sh
 
-  Lint-FFI:
-    runs-on: ubuntu-latest
-    steps:
-      - name: "Checkout repo"
-        uses: actions/checkout@v4
-      - name: "Use cache"
-        uses: Swatinem/rust-cache@v2
-      - name: "Install nix"
-        uses: DeterminateSystems/determinate-nix-action@main
-      - name: "Use nix cache"
-        uses: DeterminateSystems/magic-nix-cache-action@main
-      - name: "Run linting check"
-        run: cd payjoin-ffi && nix develop -c ./contrib/lint.sh
-
   Lint:
     runs-on: ubuntu-latest
     steps: