update version in __init__.py

[hhalaby]

Terminal Output

Collecting git+https://github.com/usgs/MapIO.git@0.8 (from -r pre-prod/mapio.txt (line 1))
  Cloning https://github.com/usgs/MapIO.git (to revision 0.8) to /tmp/pip-req-build-_oc19ddp
  Running command git clone --filter=blob:none --quiet https://github.com/usgs/MapIO.git /tmp/pip-req-build-_oc19ddp
  Resolved https://github.com/usgs/MapIO.git to commit cd028f3373e4166cef68a3e0a77b5ef1ee062c88
  Preparing metadata (setup.py) ... done
Building wheels for collected packages: mapio
  Building wheel for mapio (setup.py) ... done
  Created wheel for mapio: filename=mapio-0.6.2-py3-none-any.whl size=74541 sha256=b9df6b69d6af30f02145a1a202a012e804a7c9050281db2d35265be73ffb6ada
  Stored in directory: /tmp/pip-ephem-wheel-cache-n20ilnez/wheels/26/23/55/f42eb8e60e4cae20a39cc6b48149fdc5e0046b7715b2da26ef
Successfully built mapio
Installing collected packages: mapio
Successfully installed mapio-0.6.2

it should say "successfully installed mapio-0.8"