Add Python 3.10 support and tests (#9077)

Fixes https://github.com/certbot/certbot/issues/9058.

The changes to the CI config are equivalent to the ones made in https://github.com/certbot/certbot/pull/8460.

Other than ignoring some warnings raised by botocore, the main additional work that had to be done here was switching away from using `distutils.version.LooseVersion` since the entire `distutils` module was deprecated in Python 3.10. To do that, I took a few different approaches:

* If the version strings being parsed are from Python packages such as Certbot or setuptools, I switched to using [pkg_resources.parse_version](https://setuptools.pypa.io/en/latest/pkg_resources.html#parsing-utilities) from `setuptools`. This functionality has been available since [setuptools 8.0 from 2014](https://setuptools.pypa.io/en/latest/history.html#id865).
* If the version strings being parsed are not from Python packages, I added code equivalent to `distutils.version.LooseVersion` in `certbot.util.parse_loose_version`.
* The code for `CERTBOT_PIP_NO_BINARY` can be completely removed since that variable isn't used or referenced anywhere in this repo.

* add python 3.10 support

* make some version changes

* don't use looseversion in setup.py

* switch to pkg_resources

* deprecate get_strict_version

* fix route53 tests

* remove unused CERTBOT_PIP_NO_BINARY code

* stop using distutils in letstest

* add unit tests

* more changelog entries

.azure-pipelines/templates/jobs/extended-tests-jobs.yml

@@ -4,7 +4,7 @@ jobs:
       - name: IMAGE_NAME
         value: ubuntu-18.04
       - name: PYTHON_VERSION
-        value: 3.9
+        value: 3.10
       - group: certbot-common
     strategy:
       matrix:
@@ -17,6 +17,9 @@ jobs:
         linux-py38:
           PYTHON_VERSION: 3.8
           TOXENV: py38
+        linux-py39:
+          PYTHON_VERSION: 3.9
+          TOXENV: py39
         linux-py37-nopin:
           PYTHON_VERSION: 3.7
           TOXENV: py37
@@ -71,6 +74,14 @@ jobs:
           PYTHON_VERSION: 3.9
           TOXENV: integration
           ACME_SERVER: boulder-v2
+        linux-boulder-v1-py310-integration:
+          PYTHON_VERSION: 3.10
+          TOXENV: integration
+          ACME_SERVER: boulder-v1
+        linux-boulder-v2-py310-integration:
+          PYTHON_VERSION: 3.10
+          TOXENV: integration
+          ACME_SERVER: boulder-v2
         nginx-compat:
           TOXENV: nginx_compat
         linux-integration-rfc2136:

.azure-pipelines/templates/jobs/standard-tests-jobs.yml

@@ -1,16 +1,16 @@
 jobs:
   - job: test
     variables:
-      PYTHON_VERSION: 3.9
+      PYTHON_VERSION: 3.10
     strategy:
       matrix:
         macos-py36:
           IMAGE_NAME: macOS-10.15
           PYTHON_VERSION: 3.6
           TOXENV: py36
-        macos-py39:
+        macos-py310:
           IMAGE_NAME: macOS-10.15
-          PYTHON_VERSION: 3.9
+          PYTHON_VERSION: 3.10
           TOXENV: py39
         windows-py36:
           IMAGE_NAME: vs2017-win2016
@@ -36,17 +36,17 @@ jobs:
           IMAGE_NAME: ubuntu-18.04
           PYTHON_VERSION: 3.6
           TOXENV: py36
-        linux-py39-cover:
+        linux-py310-cover:
           IMAGE_NAME: ubuntu-18.04
-          PYTHON_VERSION: 3.9
-          TOXENV: py39-cover
-        linux-py39-lint:
+          PYTHON_VERSION: 3.10
+          TOXENV: py310-cover
+        linux-py310-lint:
           IMAGE_NAME: ubuntu-18.04
-          PYTHON_VERSION: 3.9
+          PYTHON_VERSION: 3.10
           TOXENV: lint-posix
-        linux-py39-mypy:
+        linux-py310-mypy:
           IMAGE_NAME: ubuntu-18.04
-          PYTHON_VERSION: 3.9
+          PYTHON_VERSION: 3.10
           TOXENV: mypy-posix
         linux-integration:
           IMAGE_NAME: ubuntu-18.04