Update vendored requests to 2.25.1

Updates certifi to 2021.5.30
Updates chardet to 4.0.0
Updates idna to 2.10
Updates urllib3 to 1.26.13

libs/common/requests/compat.py

@@ -43,6 +43,7 @@ if is_py2:
     import cookielib
     from Cookie import Morsel
     from StringIO import StringIO
+    # Keep OrderedDict for backwards compatibility.
     from collections import Callable, Mapping, MutableMapping, OrderedDict
 
 
@@ -59,6 +60,7 @@ elif is_py3:
     from http import cookiejar as cookielib
     from http.cookies import Morsel
     from io import StringIO
+    # Keep OrderedDict for backwards compatibility.
     from collections import OrderedDict
     from collections.abc import Callable, Mapping, MutableMapping