Bump markdown2 from 2.4.3 to 2.4.5

Bumps [markdown2](https://github.com/trentm/python-markdown2) from 2.4.3 to 2.4.5.
- [Release notes](https://github.com/trentm/python-markdown2/releases)
- [Changelog](https://github.com/trentm/python-markdown2/blob/master/CHANGES.md)
- [Commits](trentm/python-markdown2@2.4.3...2.4.5)

---
updated-dependencies:
- dependency-name: markdown2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -9,7 +9,7 @@ python-memcached==1.59
 feedparser==6.0.10
 gunicorn==20.1.0
 html2text==2020.1.16
-markdown2==2.4.3
+markdown2==2.4.5
 oauth2client==4.1.3
 psycopg2cffi==2.9.0
 python-dateutil==2.8.2