Fix pylint and mypy errors

* gn3/db/sample_data.py (get_trait_csv_sample_data): Pass __query
directly to cursor.execute.  Rename value to _value in for loop to
make mypy pass.
* gn3/db_utils.py (Connection): Add class docstring.
(Connection.cursor): Add docstring.
* mypy.ini: Add an entry for xapian.

1 files changed, 3 insertions, 0 deletions

diff --git a/mypy.ini b/mypy.ini
index 58f0f88..0880695 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -45,3 +45,6 @@ ignore_missing_imports = True
 
 [mypy-scripts.argparse_actions.*]
 ignore_missing_imports = True
+
+[mypy-xapian.*]
+ignore_missing_imports = True