DOC: fix a warning using obsolete package (#39969)

Author: partev

doc/source/user_guide/style.ipynb

@@ -1154,7 +1154,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from IPython.html import widgets\n",
+    "from ipywidgets import widgets\n",
     "@widgets.interact\n",
     "def f(h_neg=(0, 359, 1), h_pos=(0, 359), s=(0., 99.9), l=(0., 99.9)):\n",
     "    return df.style.background_gradient(\n",