Re-compiling dependencies in examples [ci skip]

Because security alert from GitHub came

examples/prod-requirements.txt

@@ -2,11 +2,11 @@
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile --output-file prod-requirements.txt prod-requirements.in
+#    pip-compile -U prod-requirements.in
 #
 click==7.0                # via flask
 flask==1.0.2
 itsdangerous==1.1.0       # via flask
-jinja2==2.10              # via flask
-markupsafe==1.1.0         # via jinja2
-werkzeug==0.14.1          # via flask
+jinja2==2.10.1            # via flask
+markupsafe==1.1.1         # via jinja2
+werkzeug==0.15.2          # via flask