Remove cmake version check from setup.py (#408)

There is a cmake version is already specified in `CMakeLists.txt` and
this Windows-specific check in setup.py isn't required (and wasn't
accurate anyway)

setup.py

@@ -1,13 +1,11 @@
 #!/usr/bin/python3
 import os
-import re
 import sys
 import platform
 import subprocess
 
 from setuptools import setup, Extension
 from setuptools.command.build_ext import build_ext
-from distutils.version import LooseVersion
 
 
 class CMakeExtension(Extension):
@@ -19,21 +17,14 @@ def __init__(self, name, sourcedir=""):
 class CMakeBuild(build_ext):
     def run(self):
         try:
-            out = subprocess.check_output(["cmake", "--version"])
+            subprocess.check_output(["cmake", "--version"])
         except OSError:
             raise RuntimeError(
                 "CMake must be installed to build"
                 + " the following extensions: "
                 + ", ".join(e.name for e in self.extensions)
             )
 
-        if platform.system() == "Windows":
-            cmake_version = LooseVersion(
-                re.search(r"version\s*([\d.]+)", out.decode()).group(1)
-            )
-            if cmake_version < "3.1.0":
-                raise RuntimeError("CMake >= 3.1.0 is required on Windows")
-
         for ext in self.extensions:
             self.build_extension(ext)