CI: avoid heredoc EOF parsing in nodeid step

.github/workflows/build-ultraplot.yml

@@ -135,26 +135,22 @@ jobs:
           echo "TEST_NODEIDS=${TEST_NODEIDS}"
           # Save PR-selected nodeids for reuse after checkout (if provided)
           if [ "${TEST_MODE}" = "selected" ] && [ -n "${TEST_NODEIDS}" ]; then
-            python - <<'PY'
-            import json
-            import os
-
-            raw = os.environ.get("TEST_NODEIDS", "").strip()
-            nodeids = []
-            if raw and raw != "[]":
-                try:
-                    parsed = json.loads(raw)
-                except json.JSONDecodeError:
-                    parsed = raw.split()
-                if isinstance(parsed, str):
-                    parsed = [parsed]
-                if isinstance(parsed, list):
-                    nodeids = [item for item in parsed if isinstance(item, str) and item]
-            with open("/tmp/pr_selected_nodeids.txt", "w", encoding="utf-8") as fh:
-                for nodeid in nodeids:
-                    fh.write(f"{nodeid}\n")
-            print(f"Selected nodeids parsed: {len(nodeids)}")
-            PY
+            python -c 'import json, os
+raw = os.environ.get("TEST_NODEIDS", "").strip()
+nodeids = []
+if raw and raw != "[]":
+    try:
+        parsed = json.loads(raw)
+    except json.JSONDecodeError:
+        parsed = raw.split()
+    if isinstance(parsed, str):
+        parsed = [parsed]
+    if isinstance(parsed, list):
+        nodeids = [item for item in parsed if isinstance(item, str) and item]
+with open("/tmp/pr_selected_nodeids.txt", "w", encoding="utf-8") as fh:
+    for nodeid in nodeids:
+        fh.write(f"{nodeid}\n")
+print(f"Selected nodeids parsed: {len(nodeids)}")'
           else
             : > /tmp/pr_selected_nodeids.txt
           fi