Update makecpt baseline images for GMT 6.2.0rc1 (#1231)

* Mark makecpt tests with xfail

Co-authored-by: Wei Ji <[email protected]>

Author: Meghan Jones

pygmt/tests/baseline/test_makecpt_categorical.png.dvc

@@ -1,4 +1,4 @@
 outs:
-- md5: 3452d1c57e68d0ff7a326a6fa35cbf5d
-  size: 4079
+- md5: 9a8c5ecec5f8962987635057f577a01c
+  size: 6029
   path: test_makecpt_categorical.png

pygmt/tests/baseline/test_makecpt_cyclic.png.dvc

@@ -1,4 +1,4 @@
 outs:
-- md5: 479dbbd853e31354d825e0e23e123920
-  size: 3925
+- md5: 4ad410eb2843b3b47818121563c79254
+  size: 4628
   path: test_makecpt_cyclic.png

pygmt/tests/test_makecpt.py

@@ -150,6 +150,10 @@ def test_makecpt_continuous(grid):
     return fig
 
 
+@pytest.mark.xfail(
+    reason="Flaky test only passes with pytest on single module"
+    "See https://github.com/GenericMappingTools/pygmt/issues/1242"
+)
 @pytest.mark.mpl_image_compare
 def test_makecpt_categorical(region):
     """
@@ -161,6 +165,10 @@ def test_makecpt_categorical(region):
     return fig
 
 
+@pytest.mark.xfail(
+    reason="Flaky test only passes with pytest on single module"
+    "See https://github.com/GenericMappingTools/pygmt/issues/1242"
+)
 @pytest.mark.mpl_image_compare
 def test_makecpt_cyclic(region):
     """