chore(ci): freeze node to 10.4 until mock-fs is fixed

[Yeti-or]

cc @zxqfox it's a problem inside mock-fs: https://github.com/tschaub/mock-fs/issues/238 let's merge quick fix right now and create issue about unfreezing node version:

• We could find a way to fix mock-fs
• We could drop mock-fs