Bump pytest to 5.2.3 (#28785)

requirements_test.txt

@@ -14,6 +14,6 @@ pytest-aiohttp==0.3.0
 pytest-cov==2.8.1
 pytest-sugar==0.9.2
 pytest-timeout==1.3.3
-pytest==5.2.2
+pytest==5.2.3
 requests_mock==1.7.0
 responses==0.10.6