Update renovate.json

[Kircheneer]

Currently renovate appears to be using poetry 1.1.13, which is a problem because of this. According to this, we can apply constraints to the Poetry version used by renovate with the change I did here.

[glennmatthews]

Any way to prove that this does what it says? :-)

[Kircheneer]

There is the way of "install the whole renovate stack locally and see what it does", I was looking to avoid that but should probably go do it..

[Kircheneer]

Check this for proof @glennmatthews 👍🏻

[Kircheneer]

@glennmatthews @chadell can we move this forward? I'd like to get the whole renovate configuration thing wrapped up 🚀