Fix typos discovered by codespell (#7371)

Author: cclauss

tests/test_requests.py

@@ -737,7 +737,7 @@ def test_basicauth_with_netrc_leak(self, httpbin):
 
         try:
             # Should use netrc
-            # Make sure that we don't use the example.com credentails
+            # Make sure that we don't use the example.com credentials
             # for the request
             r = requests.get(url)
             assert r.status_code == 200