* Versioning logic moved into separate file; versioning is determined in that
file and appropriate facts are set.
* Removed 'gitea_dl_url' from defaults/main.yml. This is now a generated fact
from tasks/set_version.yml.
* Remote gitea version is only checked if 'latest' is set, otherwise no logic
change.
* 'gitea_version' used in tasks is now 'gitea_version_target'. This is the
target install version after versioning logic is applied. No change to end
user usage of 'gitea_version' in defaults/main.yml.
* Updated documentation with usage and removal of 'gitea_dl_url'.