chore(ci): Add workflow to update pixi lock on PRs

Author: effigies

.github/workflows/pixi-lock.yml

@@ -0,0 +1,35 @@
+on:
+  pull_request_target:
+    paths:
+      - pyproject.toml
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-lockfile:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - name: Checkout pull request
+        uses: actions/checkout@v5
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Set git identity
+        run: |
+          git config --global user.name "nipreps[bot]"
+          git config --global user.email "[email protected]"
+      - uses: prefix-dev/[email protected]
+        with:
+          pixi-version: v0.58.0
+          run-install: false
+      - name: Install the latest version of uv
+        uses: astral-sh/setup-uv@v7
+      - name: Update lockfile
+        run: |
+          uvx datalad run -i pixi.lock -i pyproject.toml -o pixi.lock -- pixi lock
+      - name: Push updated lockfile, if needed
+        run: git push