[Bug] Unable to copy blocks

[jeremyVignelles]

When I'm in block selection mode, I'm unable to copy the block content

Steps to reproduce:

1. Go to https://editorjs.io/
2. Select several block
3. Copy the blocks, with either ctrl + C or right-click / copy
4. Go to a text editor, try to paste.
5. The blocks have not been copied

Expected behavior: The block content should have been copied

Screenshots:

Device, Browser, OS: Firefox developer 88.0b6 on Windows 10 20H2

Editor.js version: The one live at editorjs.io