Update butterfly-pubsub requirement from ~=2.0.0 to ~=2.1.1

Updates the requirements on butterfly-pubsub to permit the latest version.

---
updated-dependencies:
- dependency-name: butterfly-pubsub
  dependency-type: direct:production
...

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

requirements.txt

@@ -33,4 +33,4 @@ https://github.com/mapbox/vector-tile-base/archive/refs/heads/master.tar.gz
 --extra-index-url https://git.sectio-aurea.org/api/v4/groups/262/-/packages/pypi/simple
 flask-openapi~=2.0.3
 validataclass-search-queries~=0.5.0
-butterfly_pubsub~=2.0.0
+butterfly_pubsub~=2.1.1