[fix] ./manage pyenv.install - die when pyenv build fails

ERROR: When pyenv build fails, the pyenv command runs into a recursion [1]:

    ....
    BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  ERROR: Cannot install idna==3.1 and requests[socks]==2.25.1 because these package versions have conflicting dependencies.
    BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV
    BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  BUILDENV  The conflict is caused by:

[1] https://github.com/return42/searx-next/pull/4#issuecomment-821999497



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>