Bump pytest from 5.0.1 to 5.3.5 in /requirements

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.0.1 to 5.3.5.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/5.0.1...5.3.5)

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

requirements/dev.txt

@@ -1,8 +1,8 @@
 # Dependencies needed only for development/testing.
 
-pytest==5.0.1 \
-    --hash=sha256:a736fed91c12681a7b34617c8fcefe39ea04599ca72c608751c31d89579a3f77 \
-    --hash=sha256:6ef6d06de77ce2961156013e9dff62f1b2688aa04d0dc244299fe7d67e09370d
+pytest==5.3.5 \
+    --hash=sha256:ff615c761e25eb25df19edddc0b970302d2a9091fbce0e7213298d85fb61fef6 \
+    --hash=sha256:0d5fe9189a148acc3c3eb2ac8e1ac0742cb7618c084f3d228baaec0c254b318d
 
 django-debug-toolbar==2.0 \
     --hash=sha256:9a23ada2e43cd989195db3c18710b5d7451134a0d48127ab64c1d2ad81700342 \