Move away from imp

[PCManticore]

Now that we only support Python 3, we should move away from imp to importlib.

Check https://bugs.python.org/issue34056 and #593 (comment).

[sushobhit27]

@PCManticore can I work on this as this seems to be simple find replace issue.

[PCManticore]

@sushobhit27 Please do!

[pkolbus]

I'm running into the DeprecationWarning as well, as enabling this warning is recommended by the Python 3.9 release notes; PEP 594 indicates a desire to remove imp in 3.10 which is now starting development. @degustaf has made excellent headway on this in #686 but this work has stalled.

@PCManticore @degustaf any objection if I take this (and #681) over?

[degustaf]

@pkolbus I have no issue with you taking this over. I have been busy on other things.