Fixes unit test for newer versions of psycopg2.

Version 2.8.0 of Psycopg2 introduces more granular errors
for queries. This commit fixes a unit test to assert on
the specific error instead of the now-updated base class.

The previous matching class was ProgrammingError.
For the specific test, it is now UndefinedColumn,
which is a subclass of ProgrammingError.

Author: chanchiem

tests/ext/psycopg2/test_psycopg2.py

@@ -144,7 +144,7 @@ def test_execute_bad_query():
     assert sql['database_version']
 
     exception = subsegment.cause['exceptions'][0]
-    assert exception.type == 'ProgrammingError'
+    assert exception.type == 'UndefinedColumn'
 
 
 def test_register_extensions():