py-bcrypt is unmaintained and support will be dropped in passlib 1.8. The
recommended option is bcrypt.
* gnu/packages/python-crypto.scm (python-passlib)[propagated-inputs]: Remove
python-py-bcrypt. Add python-bcrypt.
[arguments]<#:phases>: Don't return #t.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>