We shouldn't pro-actively raise an import error when clients are using Python 3.6. It's true that many scripts won't support Python 3.6, but that isn't nessesarily true for webkitpy as a whole. In any case, for the scripts which this _is_ the case, we will end up with an import exception anyways. Convert this import error to a printed error message instead.
<rdar://problem/112415698>
Pull request: https://github.com/WebKit/WebKit/pull/15886
Committed 266104@main (7e218f4ef9d6): <https://commits.webkit.org/266104@main> Reviewed commits have been landed. Closing PR #15886 and removing active labels.