Fix main for new cryptography 37.0.0 release (#445)

* Fix empty check for openssl_pkcs12 tests.

* Remove unnecessary imports.

* Prevent crash if PyOpenSSL cannot be imported because of an AttributeError.

* Add changelog fragment.

* Fix constraints file.

* Use Python 2.7 instead of 3.5 for 2.9 cloud tests (pip module is broken).

* Prevent upgrading cryptography on ansible-core 2.12's default container with Python 3.9.

plugins/module_utils/crypto/module_backends/certificate_selfsigned.py

@@ -12,8 +12,6 @@ import os
 
 from random import randrange
 
-from ansible.module_utils.common.text.converters import to_bytes
-
 from ansible_collections.community.crypto.plugins.module_utils.crypto.support import (
     get_relative_time_option,
     select_message_digest,
@@ -31,11 +29,6 @@ from ansible_collections.community.crypto.plugins.module_utils.crypto.module_bac
     CertificateProvider,
 )
 
-try:
-    from OpenSSL import crypto
-except ImportError:
-    pass
-
 try:
     import cryptography
     from cryptography import x509