feat: Larger histogram plot if table only has one column (#716)

### Summary of Changes
- Table.plot_histogram() with only one column is now bigger.
- updated Test Image

src/safeds/data/tabular/containers/_table.py

@@ -2267,8 +2267,12 @@ def plot_histograms(self, *, number_of_bins: int = 10) -> Image:
         n_cols = min(3, self.number_of_columns)
         n_rows = 1 + (self.number_of_columns - 1) // n_cols
 
-        one_col = n_cols == 1 and n_rows == 1
-        fig, axs = plt.subplots(n_rows, n_cols, tight_layout=True, figsize=(n_cols * 3, n_rows * 3))
+        if n_cols == 1 and n_rows == 1:
+            fig, axs = plt.subplots(1, 1, tight_layout=True)
+            one_col = True
+        else:
+            fig, axs = plt.subplots(n_rows, n_cols, tight_layout=True, figsize=(n_cols * 3, n_rows * 3))
+            one_col = False
 
         col_names = self.column_names
         for col_name, ax in zip(col_names, axs.flatten() if not one_col else [axs], strict=False):