Update dependencies (#572)

Co-authored-by: henryiii <henryiii@users.noreply.github.com>

cibuildwheel/resources/constraints-python36.txt

@@ -20,7 +20,7 @@ six==1.15.0
     # via virtualenv
 typing-extensions==3.7.4.3
     # via importlib-metadata
-virtualenv==20.4.0
+virtualenv==20.4.2
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
@@ -34,5 +34,5 @@ zipp==3.4.0
 # The following packages are considered to be unsafe in a requirements file:
 pip==21.0.1
     # via -r cibuildwheel/resources/constraints.in
-setuptools==52.0.0
+setuptools==53.0.0
     # via -r cibuildwheel/resources/constraints.in