make python: don't instruct pip on how to use wheels
make python: don't instruct pip on how to use wheels

pip manages wheels on its own now, and these command line options are
outdated (and the make target is not used).

johnwallace123/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,dnanexus/dx-toolkit