Fix deploy template tests on Rocky and earlier

Version 1.54 is from Stein, we cannot use it on older versions. We actually
don't need to specify it, since the lowest version is used by default.

Depends-On: https://review.openstack.org/#/c/642435/
Change-Id: I8edff72f869d83ff7f192f43a3236a634c294e2b
diff --git a/ironic_tempest_plugin/tests/api/admin/test_deploy_templates.py b/ironic_tempest_plugin/tests/api/admin/test_deploy_templates.py
index b60e9b3..2de93e8 100644
--- a/ironic_tempest_plugin/tests/api/admin/test_deploy_templates.py
+++ b/ironic_tempest_plugin/tests/api/admin/test_deploy_templates.py
@@ -199,15 +199,6 @@
 class TestDeployTemplatesOldAPI(base.BaseBaremetalTest):
     """Negative tests for deploy templates using an old API version."""
 
-    max_microversion = '1.54'
-
-    def setUp(self):
-        super(TestDeployTemplatesOldAPI, self).setUp()
-        self.useFixture(
-            api_microversion_fixture.APIMicroversionFixture(
-                self.max_microversion)
-        )
-
     @decorators.attr(type=['negative'])
     @decorators.idempotent_id('e9481a0d-23e0-4757-bc11-c3c9ab9d3839')
     def test_create_deploy_template_old_api(self):