Update Python requests package to 2.20.0

See https://2.python-requests.org/en/master/community/updates/#id8.
This is currently only used in the tests, but it's best to fix
this now.

While here, remove now-false not about required support for Python
2.6.

Change-Id: I092a641a12f38cdb45b0062c31ffb51c0c664800
Reviewed-on: http://gerrit.cloudera.org:8080/17215
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Zoltan Borok-Nagy <boroknagyz@cloudera.com>
Reviewed-by: Joe McDonnell <joemcdonnell@cloudera.com>

infra/python/deps/requirements.txt

@@ -17,8 +17,6 @@
 
 # To download requirements use the download_requirements script in this dir.
 
-# Remember, all modules below need to support python 2.6.
-
 # Dependents are indented. Dependents that have multiple parents are not listed
 # multiple times (though maybe they could be).
 
@@ -50,7 +48,6 @@ python-magic == 0.4.11
 # attempting to install pywebhdfs (https://github.com/pywebhdfs/pywebhdfs/issues/52).
 # pywebhdfs itself will be installed in stage 2.
   pbr == 3.1.1
-requests == 2.7.0
 # Newer versions of setuptools don't support Python 2.6
 setuptools == 36.8.0
 setuptools-scm == 1.15.4

infra/python/deps/stage2-requirements.txt

@@ -18,8 +18,6 @@
 # This file contains packages that have dependencies in requirements.txt and that have to
 # be installed in a separate invocation of pip.
 
-# Remember, all modules below need to support python 2.6.
-
 # Requires setuptools-scm
 pytest == 2.9.2
   py == 1.4.32
@@ -34,3 +32,9 @@ hdfs == 2.0.2
 
 # Requires pbr
 pywebhdfs == 0.3.2
+
+requests == 2.20.0
+   chardet == 3.0.4
+   idna == 2.8
+   urllib3 == 1.21.1
+   certifi == 2020.12.5