Set max_microversion 2.43 for virtual_interfaces tests

The compute os-virtual-interfaces API is deprecated from the
Microversion 2.44, so we should set max_microversion = '2.43'
for compute virtual_interfaces tests.

Change-Id: Ie1793802fa33898ffbdad16b58b085894e66d4d1
ref: https://developer.openstack.org/api-ref/compute/#list-virtual-interfaces
diff --git a/tempest/api/compute/servers/test_virtual_interfaces.py b/tempest/api/compute/servers/test_virtual_interfaces.py
index 5fb1711..f810ec5 100644
--- a/tempest/api/compute/servers/test_virtual_interfaces.py
+++ b/tempest/api/compute/servers/test_virtual_interfaces.py
@@ -28,6 +28,7 @@
 # TODO(mriedem): Remove this test class once the nova queens branch goes into
 # extended maintenance mode.
 class VirtualInterfacesTestJSON(base.BaseV2ComputeTest):
+    max_microversion = '2.43'
 
     depends_on_nova_network = True
 
diff --git a/tempest/api/compute/servers/test_virtual_interfaces_negative.py b/tempest/api/compute/servers/test_virtual_interfaces_negative.py
index ec4d7a8..f6e8bc9 100644
--- a/tempest/api/compute/servers/test_virtual_interfaces_negative.py
+++ b/tempest/api/compute/servers/test_virtual_interfaces_negative.py
@@ -23,6 +23,7 @@
 # TODO(mriedem): Remove this test class once the nova queens branch goes into
 # extended maintenance mode.
 class VirtualInterfacesNegativeTestJSON(base.BaseV2ComputeTest):
+    max_microversion = '2.43'
 
     depends_on_nova_network = True