Remove manual fix for twisted in CI (#8847)

Author: alex

Diff for: .github/downstream.d/twisted.sh

@@ -5,7 +5,7 @@ case "${1}" in
         git clone --depth=1 https://github.com/twisted/twisted
         cd twisted
         git rev-parse HEAD
-        pip install ".[all_non_platform]" "pyasn1!=0.5.0"
+        pip install ".[all_non_platform]"
         ;;
     run)
         cd twisted