[PATCH] tox: 'flake' -> 'flake8'

[Finucane, Stephen]

On 12 Jan 18:59, Stephen Finucane wrote:
> The 'flake8' target specified the wrong dependendency. Resolve this.
> 
> Signed-off-by: Stephen Finucane <stephen.finucane at intel.com>

Merged.