Figure out a way to retain python2 compatibility while modularizing cqlsh

[jeffwidman]

The changes in #7 are great, but break under py2: #11

I like the changes in #7 and don't want to revert them, so see if there's a straightforward way to tweak it to make it compatible with py2.

[bschoening]

FYI, Cassandra 4.1 scheduled for April 2022 release will remove python 2.7 compatibility.

[jeffwidman]

Sounds like an easy way to deal with this.

We'll just need to be sure the Classifiers and python_requires sections are updated appropriately before cutting that release.

(and also pull in the 4.1 version of the cqlsh code)

[jeffwidman]

I'm going to close this... even though it's not present here, cassandra trunk already removed Python 2, which will arrive with cassandra 4.1. I opened a draft PR so once it's ready/merged, this will be a non-issue. In the meantime, our master branch here is still broken under Python 2, and that's just fine since the actual release on PyPI is still python 2 compatible.