test_StrCategoryLocator using parameterized plotter (matplotlib#19963)

The plot function in `test_StrCategoryLocator1` in `test_category` is parametrized, but the test was using `ax.plot` so this PR has it use the parameter instead.

Author: story645

lib/matplotlib/tests/test_category.py

@@ -140,7 +140,7 @@ def test_StrCategoryLocator(self):
 
     @pytest.mark.parametrize("plotter", PLOT_LIST, ids=PLOT_IDS)
     def test_StrCategoryLocatorPlot(self, ax, plotter):
-        ax.plot(["a", "b", "c"])
+        plotter(ax, [1, 2, 3], ["a", "b", "c"])
         np.testing.assert_array_equal(ax.yaxis.major.locator(), range(3))