add CONTRIBUTING.md

pybis/src/python/CONTRIBUTING.md

+# Contributing to pyBIS
+
+## Run the tests
+
+In order to avoid endless mocking, the tests rely on a locally running instance of openBIS.
+
+- create a folder to store the openBIS state
+- mkdir -p ~/openbis_state
+- Copy & paste the command below to download the openBIS docker image and run it locally on port 8443:
+
+```sh
+docker run -e SERVER_HOST_PORT=localhost:8443 -e GROUP_ID=12940 -e GROUP_NAME="docker-host-folder-group" -e CORE_PLUGINS='enabled-modules = monitoring-support, dropbox-monitor, dataset-uploader, dataset-file-search, xls-import, openbis-sync, eln-lims, eln-lims-life-sciences' -v ~/openbis_state:/home/openbis/openbis_state -p 8443:443 openbis/debian-openbis:20.10.2.3
+```
+
+Once the local openBIS instance is up and running, run the tests:
+
+```bash
+pytest tests
+```
+
+## Make a release
+
+- `git flow release start pybis-1.32.0`
+- add the most important changes to CHANGELOG.md
+- bump the version number in `setup.py` and `/pybis/__init__.py`
+  - increase the last digit +1 for bugfixes
+  - increase the middle digit +1 for improvements and added features
+  - increase the first digit +1 for breaking changes and backward-incompatibilities
+- after commiting, finish the release with `git flow release finish pybis-1.32.0`
+- create a distribution: `python setup.py sdist`
+- upload the distribution: `twine upload dist/PyBIS-1.32.0.tar.gz`
+
+## Make a pre-release
+
+- set the version number in `setup.py` to `1.32.0rc1` (to specify a release candidate, for example)
+- see https://peps.python.org/pep-0440/
+- create a distribution: `python setup.py sdist`
+- upload the distribution: `twine upload dist/PyBIS-1.32.0rc1.tar.gz`
+- people will be able to install the test distribution using `pip install PyBIS==1.32.0rc1`
+- a normal `pip install pybis` will not install a pre-release, only stable releases