* Remove Ubuntu 16.04 (Xenial Xerus) from CI.
* Removing PyOpenSSL backend from everywhere but openssl_pkcs12.
* Remove PyOpenSSL support from module_utils that's not needed for openssl_pkcs12.
* Add changelog fragment.
* Improve openssh_* tests.
* Use 2048 instead of 4096 bit keys in many places.
ci_complete
* Parameterize default RSA key length for tests.
* Reduce default RSA key size to 1024.
ci_complete
* Fix error.
ci_complete
* Use variable more often.
* Use 2048 bits for RSA keys for certificates on RHEL8 and CentOS8.
ci_complete
* Fix missing constant.
ci_complete
* Print default key sizes.
* Extract doc fragment from openssl_csr.
* Refactor openssl_csr module into backend + module.
* Add openssl_csr_pipe module.
* Add seealso references.
* ...
* Use /dev/stdin instead of -, which seems to be only supported by newer openssl versions.
* Bump version.
* DRY: use select_message_digest.
* Fix deprecation version in docs.
* Docs improvements.
* Improve argument spec handling for module backends.
* Linting.
* Fix linting problems by using kwargs.
