Bump werkzeug from 0.15.4 to 0.15.5 in /requirements

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.15.4 to 0.15.5.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/master/CHANGES.rst)
- [Commits](https://github.com/pallets/werkzeug/compare/0.15.4...0.15.5)

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

requirements/dev.txt

@@ -27,9 +27,9 @@ PyPOM==2.2.0 \
     --hash=sha256:6772ec99f0a21a5bdc8c092007a8c813ed18359e67ed70258bbb233df5e28829
 
 # Required by django-extension's runserver_plus command.
-Werkzeug==0.15.4 \
-    --hash=sha256:865856ebb55c4dcd0630cdd8f3331a1847a819dda7e8c750d3db6f2aa6c0209c \
-    --hash=sha256:a0b915f0815982fb2a09161cb8f31708052d0951c3ba433ccc5e1aa276507ca6
+Werkzeug==0.15.5 \
+    --hash=sha256:87ae4e5b5366da2347eb3116c0e6c681a0e939a33b2805e2c0cbd282664932c4 \
+    --hash=sha256:a13b74dd3c45f758d4ebdb224be8f1ab8ef58b3c0ffc1783a8c7d9f4f50227e6
 
 flake8==3.7.8 \
     --hash=sha256:8e9dfa3cecb2400b3738a42c54c3043e821682b9c840b0448c0503f781130696 \