If a user uses a temporary access key for login, a session token is also
needed.
This commit adds support for it to the internal aws library and also
to the osbuild-upload-aws helper. Note that this doesn't affect the main
osbuild-composer executable nor the worker. Everything here should work
as before and session tokens are not supported. Something for a follow up
if anyone needs it.
Signed-off-by: Ondřej Budai <ondrej@budai.cz>
579a5df698