Code review comment for lp://staging/~xnox/ubuntu-terminal-app/drop-lxml-dep

Note that it's not a matter of just replacing the import, as it seems that the standard module is not a drop-in replacement for lxml.

So further code changes will be required in CMakePluginParser.py to make it work.

In any case, as discussed on IRC with balloons, I'll split the original MP to isolate this change and not block on it.