Here the version is v0.19.1 but that's just an example. This folder just explains how the image is created. Which image is USED is specified:
* In the case of tests in pytest.ini in the addopts-line (MIGHT be different in different branches)
* in the case of running `python3 -m cryptoadvance.specter bitcoind` it's using "latest" but you can override like this: `python3 -m cryptoadvance.specter bitcoind --docker-tag v0.20.0`