Upgrade to chardet 4.x

requests/__init__.py

@@ -65,10 +65,8 @@ def check_compatibility(urllib3_version, chardet_version):
     # Check chardet for compatibility.
     major, minor, patch = chardet_version.split('.')[:3]
     major, minor, patch = int(major), int(minor), int(patch)
-    # chardet >= 3.0.2, < 3.1.0
-    assert major == 3
-    assert minor < 1
-    assert patch >= 2
+    # chardet >= 3.0.2, < 5.0.0
+    assert (3, 0, 2) <= (major, minor, patch) < (5, 0, 0)
 
 
 def _check_cryptography(cryptography_version):

setup.py

@@ -42,7 +42,7 @@ if sys.argv[-1] == 'publish':
 packages = ['requests']
 
 requires = [
-    'chardet>=3.0.2,<4',
+    'chardet>=3.0.2,<5',
     'idna>=2.5,<3',
     'urllib3>=1.21.1,<1.27',
     'certifi>=2017.4.17'