Update setuptools pinned in pipstrap (#6699)

Fixes #6697.

This PR updates the version of setuptools pinned in pipstrap which works around the problems we have seen on recent OSes.

Why did I pick this version of setuptools? Because it's the latest and greatest, [supports all versions of Python that we do](https://github.com/pypa/setuptools/blob/v40.6.3/setup.py#L173), [has been out for a month and a half without the need for a point release](https://setuptools.readthedocs.io/en/latest/history.html), and has no non-optional dependencies.

For the last point about dependencies, I don't think we have too much to worry about. setuptools did have a period between versions 34.0.0 and 36.0.0 where they tried to have normal dependencies on other packages, but reverted these changes. See their [changelog for 36.0.0](https://setuptools.readthedocs.io/en/latest/history.html#v36-0-0).

You can also compare their [current setup.py file](https://github.com/pypa/setuptools/blob/v40.6.3/setup.py) to the [setup.py file for the currently pinned version](https://github.com/pypa/setuptools/blob/v29.0.1/setup.py) and you'll see [not much has changed](https://pastebin.com/nQj6d7D8). 

Not only that, but I have successfully tested these changes on:

* ubuntu18.10
* ubuntu18.04LTS
* ubuntu16.04LTS
* ubuntu14.04LTS
* ubuntu14.04LTS_32bit
* debian9
* debian8.1
* amazonlinux-2015.09.1
* amazonlinux-2015.03.1
* RHEL7
* fedora23
* fedora29
* centos7
* centos6
* freebsd11
* macOS

* Update setuptools to 40.6.3.

* Build letsencrypt-auto.

* update changelog

* Don't use pipstrap in Dockerfile.centos6.

CHANGELOG.md

@@ -19,6 +19,8 @@ Certbot adheres to [Semantic Versioning](https://semver.org/).
 * Fixed accessing josepy contents through acme.jose when the full acme.jose
   path is used.
 * Clarify behavior for deleting certs as part of revocation.
+* Update the version of setuptools pinned in certbot-auto to 40.6.3 to
+  solve installation problems on newer OSes.
 
 Despite us having broken lockstep, we are continuing to release new versions of
 all Certbot components during releases for the time being, however, the only

letsencrypt-auto-source/Dockerfile.centos6

@@ -7,9 +7,9 @@ RUN yum install -y epel-release
 
 # Install pip and sudo:
 RUN yum install -y python-pip sudo
-# Use pipstrap to update to a stable and tested version of pip
-COPY ./pieces/pipstrap.py /opt
-RUN /opt/pipstrap.py
+# Update to a stable and tested version of pip.
+# We do not use pipstrap here because it no longer supports Python 2.6.
+RUN pip install pip==9.0.1 setuptools==29.0.1 wheel==0.29.0
 # Pin pytest version for increased stability
 RUN pip install pytest==3.2.5 six==1.10.0
 

letsencrypt-auto-source/letsencrypt-auto

@@ -1272,9 +1272,9 @@ PACKAGES = maybe_argparse + [
      'pip-{0}.tar.gz'.format(PIP_VERSION),
      '09f243e1a7b461f654c26a725fa373211bb7ff17a9300058b205c61658ca940d'),
     # This version of setuptools has only optional dependencies:
-    ('59/88/2f3990916931a5de6fa9706d6d75eb32ee8b78627bb2abaab7ed9e6d0622/'
-     'setuptools-29.0.1.tar.gz',
-     'b539118819a4857378398891fa5366e090690e46b3e41421a1e07d6e9fd8feb0'),
+    ('37/1b/b25507861991beeade31473868463dad0e58b1978c209de27384ae541b0b/'
+     'setuptools-40.6.3.zip',
+     '3b474dad69c49f0d2d86696b68105f3a6f195f7ab655af12ef9a9c326d2b08f8'),
     ('c9/1d/bd19e691fd4cfe908c76c429fe6e4436c9e83583c4414b54f6c85471954a/'
      'wheel-0.29.0.tar.gz',
      '1ebb8ad7e26b448e9caa4773d2357849bf80ff9e313964bcaf79cbf0201a1648')

letsencrypt-auto-source/pieces/pipstrap.py

@@ -74,9 +74,9 @@ PACKAGES = maybe_argparse + [
      'pip-{0}.tar.gz'.format(PIP_VERSION),
      '09f243e1a7b461f654c26a725fa373211bb7ff17a9300058b205c61658ca940d'),
     # This version of setuptools has only optional dependencies:
-    ('59/88/2f3990916931a5de6fa9706d6d75eb32ee8b78627bb2abaab7ed9e6d0622/'
-     'setuptools-29.0.1.tar.gz',
-     'b539118819a4857378398891fa5366e090690e46b3e41421a1e07d6e9fd8feb0'),
+    ('37/1b/b25507861991beeade31473868463dad0e58b1978c209de27384ae541b0b/'
+     'setuptools-40.6.3.zip',
+     '3b474dad69c49f0d2d86696b68105f3a6f195f7ab655af12ef9a9c326d2b08f8'),
     ('c9/1d/bd19e691fd4cfe908c76c429fe6e4436c9e83583c4414b54f6c85471954a/'
      'wheel-0.29.0.tar.gz',
      '1ebb8ad7e26b448e9caa4773d2357849bf80ff9e313964bcaf79cbf0201a1648')