Revert "fix: fix greenlet version for compatibility with pypy (#621)"

This reverts commit 1df5a54.
The reason for that is that there was no actual user bug report for it.
If we want to add PyPi support in the future, we would also need to add
bots to ensure it works over time and reflect the changes in the docs.

Author: mxschmitt

setup.py

@@ -141,7 +141,7 @@ def run(self) -> None:
     include_package_data=True,
     install_requires=[
         "websockets>=8.1",
-        "greenlet>=0.4",
+        "greenlet>=1.0.0",
         "pyee>=8.0.1",
         "typing-extensions;python_version<='3.8'",
     ],