Consider DOI release assignment strategy

Currently the deployment strategy (https://mumot.readthedocs.io/en/latest/development.html) specifies requesting a new DOI for each release. This may not be appropriate for patch releases, unless contributors have changed. Note, however that the ORDA entry refers to a specific branch, so this will be out-of-date once a new release is made (see e.g. https://figshare.shef.ac.uk/articles/MuMoT_Release_1_0_0/7951298/1)

The strategy should be left as is, or refined and described appropriately in the docs