Update hypothesis requirement from <5.20.3 to <5.20.4

Updates the requirements on [hypothesis](https://github.com/HypothesisWorks/hypothesis) to permit the latest version.
- [Release notes](https://github.com/HypothesisWorks/hypothesis/releases)
- [Commits](HypothesisWorks/hypothesis@hypothesis-ruby-0.0.1...hypothesis-python-5.20.3)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

test_requirements.txt

@@ -1,4 +1,4 @@
 pytest<6
-hypothesis<5.20.3
+hypothesis<5.20.4
 coverage==5.2
 attrs==19.3.0