remove __init__.py from top level test folder
remove __init__.py from top level test folder

https://pytest.org/latest/goodpractises.html
It is advised to avoid __init__.py in the top level test folder in
order to easily run tests against an installed package version.

juhasch/myhdl,jandecaluwe/myhdl,j-marjanovic/myhdl,jck/myhdl,jmgc/myhdl-numeric,hgomersall/myhdl,jck/myhdl,josyb/myhdl,jandecaluwe/myhdl,j-marjanovic/myhdl,cfelton/myhdl,juhasch/myhdl,jmgc/myhdl-numeric,jck/myhdl,josyb/myhdl,hgomersall/myhdl,myhdl/myhdl,jandecaluwe/myhdl,jmgc/myhdl-numeric,j-marjanovic/myhdl,myhdl/myhdl,josyb/myhdl,hgomersall/myhdl,cfelton/myhdl,juhasch/myhdl,cfelton/myhdl,myhdl/myhdl