Bump nikola from 8.3.0 to 8.3.1

Bumps [nikola](https://github.com/getnikola/nikola) from 8.3.0 to 8.3.1.
- [Release notes](https://github.com/getnikola/nikola/releases)
- [Changelog](https://github.com/getnikola/nikola/blob/master/CHANGES.txt)
- [Commits](getnikola/nikola@v8.3.0...v8.3.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -38,7 +38,7 @@ markupsafe==2.1.3
     #   mako
 natsort==8.4.0
     # via nikola
-nikola==8.3.0
+nikola==8.3.1
     # via -r requirements.in
 piexif==1.1.3
     # via nikola