remove python 3.9 support (#10406)

Fixes https://github.com/certbot/certbot/issues/10389. you can compare
this to the PR that did this for python 3.8 at
https://github.com/certbot/certbot/pull/10077

additional changes:
- linux-py310 test is removed from extended tests, since it's now run in
standard tests. additionally, openssl will never be < 1.1.1 now, due to
https://peps.python.org/pep-0644/.
- `letstest/scripts/test_openssl_version.py` was testing functionality
that was removed in https://github.com/certbot/certbot/pull/10373 so it
was deleted

---------

Co-authored-by: Brad Warren <bmw@users.noreply.github.com>

tox.ini

@@ -52,10 +52,10 @@ commands =
 commands =
     {[base]pytest} acme certbot certbot-dns-cloudflare certbot-dns-digitalocean certbot-dns-dnsimple certbot-dns-dnsmadeeasy certbot-dns-gehirn certbot-dns-google certbot-dns-linode certbot-dns-luadns certbot-dns-nsone certbot-dns-ovh certbot-dns-rfc2136 certbot-dns-route53 certbot-dns-sakuracloud certbot-nginx certbot-apache
 
-[testenv:py3{,9,10,11,12,13}]
+[testenv:py3{,10,11,12,13}]
 commands = {[testenv:py]commands}
 
-[testenv:py3.{9,10,11,12,13}]
+[testenv:py3.{10,11,12,13}]
 commands = {[testenv:py]commands}
 
 [testenv:oldest]
@@ -65,7 +65,7 @@ commands = {[testenv:py]commands}
 #
 # This version should be kept in sync with the one declared in
 # tools/pinning/oldest/pyproject.toml.
-basepython = python3.9
+basepython = python3.10
 setenv = CERTBOT_OLDEST=1
 commands = {[testenv:py]commands}