Drop Python 3.6 support (#9216)

* Remove deprecation warnings

* update ci

* update setup.py files

* update changelog

* update pinnings

* update requests and friends

* update setuptools pin

* update setuptools pin pt2

* update pytz

* upgrade pyparsing

* upgrade boto deps

* update deps and docs

* update pyproject.toml comment

* remove trailets pin

* remove explicit PYTHON_VERSION

tools/pinning/current/pyproject.toml

@@ -6,7 +6,7 @@ authors = ["Certbot Project"]
 license = "Apache License 2.0"
 
 [tool.poetry.dependencies]
-python = "^3.6"
+python = "^3.7"
 
 # Local dependencies
 # Any local packages that have dependencies on other local packages must be
@@ -69,11 +69,6 @@ poetry = ">=1.2.0a1"
 # point, it's probably worth enumerating and pinning them (and recursing to
 # THEIR build dependencies) as well.
 setuptools-rust = "*"
-# Library traitlets is a transitive dependency of ipdb (traitlets -> ipython -> ipdb).
-# Version 5.x is incompatible with Python 3.6 but for some reasons, poetry fails to
-# add the appropriate marker and allows this version to be installed under Python 3.6.
-# We add a pinning to not create a set of requirements incompatible with Python 3.6.
-traitlets = "<5"
 
 [tool.poetry.dev-dependencies]