Update factory-boy from 3.1.0 to 3.2.0 (#308)

Author: pyup-bot

requirements_dev.txt

@@ -2,7 +2,7 @@ colour-runner==0.1.1
 coveralls==2.2.0
 coverage==5.3.1
 dj-database-url==0.5.0
-factory-boy==3.1.0
+factory-boy==3.2.0
 flake8-docstrings==1.5.0
 flake8-import-order==0.18.1
 flake8==3.8.4