Update css-tree dependency

[Semigradsky]

The current css-tree version is 2.3.1 but this package depends on ~2.2.0.
Can css-tree be updated?

[romainmenke]

Can the version constraint also be relaxed to ^2.x.x ?
We currently have multiple copies for css-tree all through the same dependency.

css-tree@2.3.1
node_modules/css-tree
  css-tree@"^2.2.1" from svgo@3.0.3
  node_modules/svgo

css-tree@2.2.1
node_modules/csso/node_modules/css-tree
  css-tree@"~2.2.0" from csso@5.0.5
  node_modules/csso
    csso@"5.0.5" from svgo@3.0.3
    node_modules/svgo

This increases download bandwidth usage, memory usage, ...

[romainmenke]

This is blocked on csstree/csstree#236