Update lxml to 4.1.0

[pyup-bot]

There's a new version of lxml available.
You are currently using 4.0.0. I have updated it to 4.1.0

These links might come in handy: PyPI | Changelog | Homepage | Bugtracker

Changelog

4.1.0

==================

Features added

• ElementPath supports text predicates for current node, like "[.='text']".

• ElementPath allows spaces in predicates.

• Custom Element classes and XPath functions can now be registered with a
  decorator rather than explicit dict assignments.

• Static Linux wheels are now built with link time optimisation (LTO) enabled.
  This should have a beneficial impact on the overall performance by providing
  a tighter compiler integration between lxml and libxml2/libxslt.

Bugs fixed

• LP1722776: Requesting non-Element objects like comments from a document with
  PythonElementClassLookup could fail with a TypeError.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[coveralls]

Coverage remained the same at 30.471% when pulling 62f3b3e on pyup-update-lxml-4.0.0-to-4.1.0 into 1b5a08d on master.