Error: Version 3.6.13 with arch x64 not found
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
It seems the py 3.6 is not available in the ubuntu-latest GHA container, - pin it to Ubuntu 20.4.
An attempt to fix the CI build (failing on the new pack contribution https://github.com/StackStorm-Exchange/exchange-incubator/pull/179)
It seems the py 3.6 is not available in the
ubuntu-latest
GHA container, - pin it to Ubuntu 20.4.