Use pip-install from setup-python #320

Job	Run time
sync / sync	52s
check / Lint translations	38s
check / Check for zero-width space characters	8s
check / Build docs (html)	7m 29s
check / Build docs (epub)	7m 22s
check / Build docs (latex)	6m 48s
check / Build docs (pdf)	-1s
	23m 16s

Provide feedback