3.0.0alpha1

Bug fixes:

• remove build and test envs after each packaging step, to avoid unsatisfiable errors #1866
• remove version pins from requirements added by run_test files (again avoid unsatisfiable errors) #1866
• fix prefix file detection picking up too many files due to env recreation #1866
• fix missing r_bin, make run_test.r scripts work #1869

Contributors:

• @msarahan