CI: skip test to work around gs bug

We are seeing failures due to, what we believe, is an issue with ghostscript or
one of its dependencies failing to properly encode the compressed fonts in an
ascii compatible way.  This appears to be a transient issue has been fixed by
subsequent release, however we have not been able to identify exactly which
dependency is problematic.

For now skip the tests and remove this at some point in the future.

Author: tacaswell

lib/matplotlib/tests/test_backend_ps.py

@@ -71,6 +71,13 @@ def test_savefig_to_stringio(format, use_log, rcParams, orientation):
 
         assert not s_buf.closed
         assert not b_buf.closed
+        if '\x80' in s_buf.getvalue():
+            pytest.skip(
+                "This appears to be the result of a bug in ghostscript or one "
+                "of its dependencies that fails to ascii85 encode the "
+                "compressed fonts which results in encoding the string as "
+                "ascii failing just below."
+            )
         s_val = s_buf.getvalue().encode('ascii')
         b_val = b_buf.getvalue()