Update assignment03_decision_trees.ipynb (Yorko#742)

Fixed plot for newer package versions:
"ValueError: Number of rows must be a positive integer, not 3.0"
"AttributeError: module 'numpy' has no attribute 'object'."

jupyter_english/assignments_demo/assignment03_decision_trees.ipynb

@@ -561,9 +561,9 @@
     "cols = 5\n",
     "rows = np.ceil(float(data_train.shape[1]) / cols)\n",
     "for i, column in enumerate(data_train.columns):\n",
-    "    ax = fig.add_subplot(rows, cols, i + 1)\n",
+    "    ax = fig.add_subplot(int(rows), cols, i + 1)\n",
     "    ax.set_title(column)\n",
-    "    if data_train.dtypes[column] == np.object:\n",
+    "    if data_train.dtypes[column] == object:\n",
     "        data_train[column].value_counts().plot(kind=\"bar\", axes=ax)\n",
     "    else:\n",
     "        data_train[column].hist(axes=ax)\n",