Add check for compatible setuptools version.

In order to avoid a recursive dependency issue when parsing
the aiohttp version during install setuptools needs:
pypa/setuptools@c457e68

This implies we need setuptools 46.4.0 or newer.

CHANGES/6205.bugfix

@@ -0,0 +1 @@
+Add check for compatible ``setuptools`` version.

setup.py

@@ -2,12 +2,19 @@
 import pathlib
 import sys
 
+from distutils.version import StrictVersion
+
 from setuptools import Extension, setup
+from setuptools import __version__ as setuptools_version
 
 if sys.version_info < (3, 7):
     raise RuntimeError("aiohttp 4.x requires Python 3.7+")
 
 
+if StrictVersion(setuptools_version) < StrictVersion('46.4.0'):
+    raise RuntimeError("aiohttp 4.x requires setuptools 46.4.0+")
+
+
 NO_EXTENSIONS = bool(os.environ.get("AIOHTTP_NO_EXTENSIONS"))  # type: bool
 HERE = pathlib.Path(__file__).parent
 IS_GIT_REPO = (HERE / ".git").exists()