Support `prompt-toolkit>=2.0.0`.

[sovknaf]

I'm running into some dependency problems. pip install ends with either:

mycli 1.18.1 has requirement prompt-toolkit<2.0.5,>=2.0.0, but you'll have prompt-toolkit 1.0.15 which is incompatible.
jupyter-console 6.0.0 has requirement prompt-toolkit<2.1.0,>=2.0.0, but you'll have prompt-toolkit 1.0.15 which is incompatible.
ipython 7.0.1 has requirement prompt-toolkit<2.1.0,>=2.0.0, but you'll have prompt-toolkit 1.0.15 which is incompatible.

or

commitizen 0.9.10 has requirement prompt-toolkit==1.0.15, but you'll have prompt-toolkit 2.0.4 which is incompatible.

depending on which order I install things. I had the same problem with dependencies on different versions of prompt-toolkit just a couple of weeks ago, between mycli and ipython, but thankfully, mycli updated its dependency recently.

It would be nice to see commitizen upgrade its dependency for prompt-toolkit, so we can have them installed in the same environment. Cheers!

[woile]

No problem, I'll update it this week

[woile]

Hey @sovknaf the underlying library used by commitizen (waaaaat), unfortunately, is using prompt-toolkit==1.0.15, and the api for 2.x of prompt-toolkit has changed a lot, so, they have no plans of updating it. I'll try to remove the dependency but it'll be some heavy work, so I cannot promise to have results soon, sorry.

[woile]

An update on this:

PyInquirer is going to prompt-toolkit 2.0 so I'll integrate it as soon as it's available.

[woile]

Version 1.0 uses questionary which also uses prompt-toolkit>2