Update pytest from 4.5.0 to 4.6.2

Author: pyup-bot

requirements.txt

@@ -15,7 +15,7 @@ pandas==0.24.2
 psycopg2==2.8.2
 pysiaf==0.2.5
 python-dateutil==2.8.0
-pytest==4.5.0
+pytest==4.6.2
 sphinx==2.0.1
 sphinx-automodapi==0.10
 sqlalchemy==1.3.3