Update docker build to use pip to install

Poetry was trying to upgrade the matching version of obspy, pip does not.

@pcain : see if this builds more reliably

added 3 commits

• 0c2b6ed2...6ce92ef6 - 2 commits from branch ghsc/geomag:master
• fe19cf31 - Update docker build to use pip to install

Compare with previous version

mentioned in commit 839f29dc

merged

mentioned in merge request !131 (merged)