Add region eu-south-2 for ec2

[manu1080]

To fix

[stdout] ** (EXIT) shutdown: failed to start child: :ec2_cluster
[stdout] ** (EXIT) an exception was raised:
[stdout] ** (RuntimeError) ec2 not supported in region eu-south-2 for partition aws
[stdout] (ex_aws 2.5.8) lib/ex_aws/config/defaults.ex:195: ExAws.Config.Defaults.fetch_or/3
[stdout] (ex_aws 2.5.8) lib/ex_aws/config/defaults.ex:178: ExAws.Config.Defaults.do_host/3
[stdout] (ex_aws 2.5.8) lib/ex_aws/config/defaults.ex:110: ExAws.Config.Defaults.get/2
[stdout] (ex_aws 2.5.8) lib/ex_aws/config.ex:96: ExAws.Config.build_base/2
[stdout] (ex_aws 2.5.8) lib/ex_aws/config.ex:69: ExAws.Config.new/2
[stdout] (libcluster_ec2 0.8.2) lib/libcluster_ec2.ex:20: ClusterEC2.get_metadata/1
[stdout] (libcluster_ec2 0.8.2) lib/strategy/tags.ex:53: ClusterEC2.Strategy.Tags.init/1
[stdout] (stdlib 7.1) gen_server.erl:2276: :gen_server.init_it/2`