Currently we require:

• Werkzeug>=0.9 (4.5 years ago) (latest 0.14)
• Jinja2>=2.4 (8 years ago) (latest 2.10)
• itsdangerous>=0.21 (4.5 years ago) (latest 0.24)
• click>=4.0 (3 years ago) (latest 6.0, stable 5.0)

Should we bump these all to the latest versions?