Allow setting channel priority

[awvwgk]

The channel priority is currently set by default to strict at

provision-with-micromamba/index.js

Line 61 in a2be56c

fs.appendFileSync(condarc, 'channel_priority: strict\n')

However, not all environments necessarily solve with strict channel priority. For those environments it would be useful to allow adjusting the channel priority to flexible.

[wwarriner]

Our project would benefit from this. We are using mamba in our CI for building our documentation. I had channels listed alphabetically (anaconda > conda-forge), which caused markdown=3.3.4 to be used instead of markdown=3.3.7, causing our fenced code blocks to render improperly. I was able to work around strict priority by flipping the order of channels. However, it isn't clear if this won't come up again as package dependencies and versions change.

Could we please have a channel_priority: flexible option?

Our repo is here: https://github.com/uabrc/uabrc.github.io

[jonashaag]

PR welcome, shouldn’t be too difficult.

You may also want to pin the markdown package