Deprecate the old API microversion fixture

We have moved the API microversion fixture to
tempest.lib.common.api_microversion_fixture location.

This commit deprecates the old fixture so that we can
remove them in Z cycle.

Change-Id: If38aa21a4cd99d2a5fe4a5c3b41214cd54f97f8d
diff --git a/releasenotes/notes/deprecate-old-api-microversion-fixture-a471aac985c0f3fb.yaml b/releasenotes/notes/deprecate-old-api-microversion-fixture-a471aac985c0f3fb.yaml
new file mode 100644
index 0000000..652f7fa
--- /dev/null
+++ b/releasenotes/notes/deprecate-old-api-microversion-fixture-a471aac985c0f3fb.yaml
@@ -0,0 +1,7 @@
+---
+deprecations:
+  - |
+    Old APIMicroversionFixture classes ``tempest.api.compute.api_microversion_fixture.APIMicroversionFixture``
+    and ``tempest.api.volume.api_microversion_fixture.APIMicroversionFixture``
+    has been deprecated for removal in favor of new location
+    ``tempest.lib.common.api_microversion_fixture.APIMicroversionFixture``