Remove xfails on solar and velo tests for GMT 6.2.0rc2 (#1297)

Author: willschlitzer

pygmt/tests/test_solar.py

@@ -112,10 +112,6 @@ def test_invalid_datetime():
         )
 
 
-@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(filename="test_solar_set_terminator_datetime.png")
 def test_solar_default_terminator():
     """

pygmt/tests/test_velo.py

@@ -26,10 +26,6 @@ def fixture_dataframe():
     )
 
 
-@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_velo_numpy_array_numeric_only(dataframe):
     """
@@ -67,10 +63,6 @@ def test_velo_without_spec(dataframe):
         fig.velo(data=dataframe)
 
 
-@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_velo_pandas_dataframe(dataframe):
     """