Update lxml to 3.8.0

[pyup-bot]

There's a new version of lxml available.
You are currently using 3.7.3. I have updated it to 3.8.0

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

Changelog

3.8.0

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

Features added

• ElementTree.write() has a new option doctype that writes out a
  doctype string before the serialisation, in the same way as tostring().

• GH220: xmlfile allows switching output methods at an element level.
  Patch by Burak Arslan.

• LP1595781, GH240: added a PyCapsule Python API and C-level API for
  passing externally generated libxml2 documents into lxml.

• GH244: error log entries have a new property path with an XPath
  expression (if known, None otherwise) that points to the tree element
  responsible for the error. Patch by Bob Kline.

• The namespace prefix mapping that can be used in ElementPath now injects
  a default namespace when passing a None prefix.

Bugs fixed

• GH238: Character escapes were not hex-encoded in the xmlfile serialiser.
  Patch by matejcik.

• GH229: fix for externally created XML documents. Patch by Theodore Dubois.

• LP1665241, GH228: Form data handling in lxml.html no longer strips the
  option values specified in form attributes but only the text values.
  Patch by Ashish Kulkarni.

• LP1551797: revert previous fix for XSLT error logging as it breaks
  multi-threaded XSLT processing.

• LP1673355, GH233: fromstring() html5parser failed to parse byte strings.

Other changes

• The previously undocumented docstring option in ElementTree.write()
  produces a deprecation warning and will eventually be removed.

3.7.4

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

Bugs fixed

• LP1551797: revert previous fix for XSLT error logging as it breaks
  multi-threaded XSLT processing.

• LP1673355, GH233: fromstring() html5parser failed to parse byte strings.

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

Happy merging! 🤖

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