Pin request dependencies for old pythons

The latest version is now incompatible with 2.7

Author: Simon Begin

constraints.txt

@@ -4,23 +4,26 @@
 #
 #    pip-compile --no-emit-trusted-host --no-index --output-file=constraints.txt setup.py test-requirements.txt
 #
-certifi==2019.11.28       # via requests
+certifi==2021.10.8        # via requests
 chardet==3.0.4            # via requests
 click==7.0                # via pip-tools
-entrypoints==0.3          # via flake8
-flake8==3.7.9
+flake8==3.8.4
 idna==2.8                 # via requests
+importlib-metadata==1.1.3  # via flake8
 mccabe==0.6.1             # via flake8
 mock==3.0.5
 nose==1.3.7
+pathlib2==2.3.7.post1     # via importlib-metadata
 pip-tools==3.9.0
-pycodestyle==2.5.0        # via flake8
-pyflakes==2.1.1           # via flake8
+pycodestyle==2.6.0        # via flake8
+pyflakes==2.2.0           # via flake8
 pyhamcrest==1.9.0
 requests==2.21.0
-six==1.14.0               # via mock, pip-tools, pyhamcrest
-typing==3.7.4.1           # via flake8
+scandir==1.10.0           # via pathlib2
+six==1.16.0               # via mock, pathlib2, pip-tools, pyhamcrest
+typing==3.10.0.0          # via flake8, pathlib2
 urllib3==1.24.3           # via requests
+zipp==1.2.0               # via importlib-metadata
 
 # The following packages are considered to be unsafe in a requirements file:
 # setuptools==43.0.0        # via pyhamcrest

requirements.txt

@@ -1 +1,2 @@
-requests
+requests==2.21.0;python_version<'3.6'
+request;python_version>='3.6'