Deprecate method get_ipv6_addr_by_EUI64

Oslo.utils provides same method get_ipv6_addr_by_EUI64,
so deprecate it in Newton and remove it in Ocata.

Co-Authored-By: guo yunxian <yunxian.guo@easystack.cn>

Change-Id: Ia72f866cda69b4f98e88936df32c76e455619d07
diff --git a/tox.ini b/tox.ini
index 05fa326..1c5c177 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,6 +16,7 @@
 setenv =
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=./tempest/tests
+    PYTHONWARNINGS=default::DeprecationWarning
 passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH OS_TEST_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 usedevelop = True
 install_command = pip install -U {opts} {packages}