Test for kerning in PDF output with type 42 font

This commit adds an image comparison test to ensure that the text in a type 42
font has proper kerning in the PDF output.

Author: sauerburger

lib/matplotlib/tests/baseline_images/test_text/text_pdf_font42_kerning.pdf

@@ -741,3 +741,10 @@ def test_parse_math():
     ax.text(0, 0, r"$ \wrong{math} $", parse_math=True)
     with pytest.raises(ValueError, match='Unknown symbol'):
         fig.canvas.draw()
+
+
+@image_comparison(['text_pdf_font42_kerning.pdf'], style='mpl20')
+def test_pdf_font42_kerning():
+    plt.rcParams['pdf.fonttype'] = 42
+    plt.figure()
+    plt.figtext(0.1, 0.5, "ATAVATAVATAVATAVATA", size=30)