fix CI runs

.github/workflows/diff-pr.yml

@@ -13,26 +13,21 @@ concurrency:
 
 jobs:
   dix:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@v31
-        with:
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-
       - name: worktree base for diff
         run: git worktree add "$RUNNER_TEMP/base" "${{ github.event.pull_request.base.sha }}"
 
       - name: build closures and render diff
         run: |
-          nix run .#ci -- diff "$RUNNER_TEMP/base" . \
+          nix run -L .#ci -- diff "$RUNNER_TEMP/base" . \
             "### System closure diff vs \`${{ github.event.pull_request.base.ref }}\`" \
             > "$RUNNER_TEMP/comment.md"
-          nix run .#ci -- inspect-diff "$RUNNER_TEMP/base" . \
+          nix run -L .#ci -- inspect-diff "$RUNNER_TEMP/base" . \
             "### Inspection diff vs \`${{ github.event.pull_request.base.ref }}\`" \
             >> "$RUNNER_TEMP/comment.md"
 
@@ -42,4 +37,4 @@ jobs:
           API: ${{ github.api_url }}
           REPO: ${{ github.repository }}
           PR: ${{ github.event.pull_request.number }}
-        run: nix run .#ci -- post-comment "<!-- dix-diff -->" "$RUNNER_TEMP/comment.md"
+        run: nix run -L .#ci -- post-comment "<!-- dix-diff -->" "$RUNNER_TEMP/comment.md"