minor missing capitalization

[cddeangelis]

In countplot(), the axis stat label is not capitalized, inconsistent with other histograms.

import seaborn as sns

iris = sns.load_dataset("iris")

fig, axs = plt.subplots(ncols=2, figsize=(15,4))
sns.countplot(data=iris, x='sepal_width', hue='species',  ax=axs[0])
sns.histplot(data=iris, x='sepal_length', hue='species',  ax=axs[1])
plt.show()

This should be fixed by changing line 2672 in categorical.py to

p.variables[count_axis] = stat.capitalize()