Tox error workaround with alternate pypy version names

[nkzou]

Tox failing due to a bug with factor names, considers "pypy" and "3.8" conflicting. This changes the actions workflow to use pypy3.8 and pypy2.7 as the names instead, and also updates the github actions dependency versions.

[skarimo]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 2 pipeline(s).