Add DIM operator to reference model

Signed-off-by: Won Jeon <won.jeon@arm.com>
Change-Id: Iea11ee5d3d98773e9c5e9b827593c05afb41ce3b
diff --git a/verif/conformance/test_select.py b/verif/conformance/test_select.py
index f4e2a61..b7bbfc3 100644
--- a/verif/conformance/test_select.py
+++ b/verif/conformance/test_select.py
@@ -506,6 +506,13 @@
     param_names = ["kernel", "shape", "type", "accum_type", "stride", "pad", "dilation"]
 
 
+class DimOeprator(Operator):
+    """Test selector for the DIM operator."""
+
+    name = "dim"
+    param_names = ["shape", "type", "axis"]
+
+
 class EqualOperator(Operator):
     """Test selector for the EQUAL operator."""