Bump factory-boy from 2.11.1 to 2.12.0

Bumps [factory-boy](https://github.com/FactoryBoy/factory_boy) from 2.11.1 to 2.12.0.
- [Release notes](https://github.com/FactoryBoy/factory_boy/releases)
- [Changelog](https://github.com/FactoryBoy/factory_boy/blob/master/docs/changelog.rst)
- [Commits](FactoryBoy/factory_boy@2.11.1...2.12.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements_test.txt

@@ -1,3 +1,3 @@
 coverage==4.5.3
-factory-boy==2.11.1
+factory-boy==2.12.0
 faker==1.0.2