Outdated requirements in biomedsheets and varfish-cli

[mikkonie]

I have discovered outdated requirements in cubi-tk, which are causing unresolvable conflicts when including cubi-tk as a dependency in other Python projects.

Offending requirements:

• jsonschema==2.5.1 in biomedsheets (currently at 4.4.0)
• cattrs<2..0,>=1.7.1 in varfish-cli (currently at 22.1.0)

I will update these and create a pull request. I would appreciate if some users of the aforementioned cubi-tk modules would test these changes to verify everything still works smoothly.

Also, if you come across other problematic dependencies, feel free to suggest them in comments so they could also be tested.

[eudesbarbosa]

I went ahead and fixed biomedsheets cause I need it working for a different project: bihealth/biomedsheets#17