alternator: restore Python2 compatibility for test_tag
alternator: restore Python2 compatibility for test_tag

... by explicitly declaring utf-8 encoding.
Message-Id: <668b0c911995f519e9af4cd7a905e33e1201dbbe@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla