Try the Twisted prerelease, which hopefully obviates installing IOCP.

Julian · Julian · commit 6e83dc76d502 · 2021-02-22T17:45:13.000-05:00
diff --git a/tox.ini b/tox.ini
@@ -43,7 +43,7 @@ deps =
 
     perf: pyperf
 
-    tests,coverage,codecov: twisted
+    tests,coverage,codecov: twisted>=21.2.0rc1
 
     coverage,codecov: coverage
     codecov: codecov
