Pick newest python for the searxng venv (master needs 3.11+; base has 3.10)

searx_runtime.py

@@ -63,8 +63,15 @@ def _venv_python() -> str | None:
     py = os.path.join(VENV_DIR, "bin", "python")
     if os.path.exists(py):
         return py
-    _log("creating venv")
-    if subprocess.run(["python3", "-m", "venv", VENV_DIR], capture_output=True).returncode != 0:
+    # Prefer the newest interpreter available (SearXNG master needs 3.11+;
+    # the container base image ships 3.10).
+    base = None
+    for cand in ("python3.13", "python3.12", "python3.11", "python3"):
+        if shutil.which(cand):
+            base = cand
+            break
+    _log(f"creating venv with {base}")
+    if not base or subprocess.run([base, "-m", "venv", VENV_DIR], capture_output=True).returncode != 0:
         _log("venv creation failed")
         return None
     _log("installing searxng deps (this takes a few minutes on first boot)")