build(deps): bump lxml from 4.6.3 to 4.6.4

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.3 to 4.6.4.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.6.3...lxml-4.6.4)

---
updated-dependencies:
- dependency-name: lxml
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -8,7 +8,7 @@ forecastiopy == 0.22
 googlemaps == 4.5.3
 imgurpython == 1.1.7
 isodate == 0.6.0
-lxml == 4.6.3
+lxml == 4.6.4
 mcstatus == 6.5.0
 multidict == 5.2.0
 nltk == 3.6.5