Bump async-solipsism from 0.8 to 0.9 (#260)

Author: llucax

pyproject.toml

@@ -102,7 +102,7 @@ dev-pytest = [
   "frequenz-repo-config[extra-lint-examples] == 0.13.8",
   "pytest-mock == 3.15.1",
   "pytest-asyncio == 1.3.0",
-  "async-solipsism == 0.8",
+  "async-solipsism == 0.9",
   "time-machine == 3.2.0",
   "hypothesis == 6.151.4",
   "frequenz-client-dispatch[cli]",