add database drivers for whitebox testing

if you are running this in a venv environment, the whitebox tests
don't actually run because there are no db drivers. Let's fix that.

Change-Id: I0524c0e0f54350f54f949aeb48b2ba23e0803f75
diff --git a/tools/test-requires b/tools/test-requires
index d3c7a1e..4801391 100644
--- a/tools/test-requires
+++ b/tools/test-requires
@@ -2,3 +2,5 @@
 pylint==0.19
 # Needed for whitebox testing
 sqlalchemy
+MySQL-python
+psycopg2