move identity_head to gears

ppcls/arch/gears/identity_head.py

+class IdentityHead(nn.Layer):
+    def __init__(self):
+        super(IdentityHead, self).__init__()
+
+    def forward(self, x, label=None):
+        return {"features": x, "logits": None}
\ No newline at end of file

tools/export_model.py

@@ -24,10 +24,9 @@ import paddle
 import paddle.nn as nn
 
 from ppcls.utils import config
-from ppcls.engine.trainer import Trainer
 from ppcls.arch import build_model, RecModel
-from ppcls.arch.backbone.base.theseus_layer import Identity
 from ppcls.utils.save_load import load_dygraph_pretrain
+from ppcls.arch.gears.identity_head import IdentityHead
 
 
 class ExportModel(nn.Layer):
@@ -62,14 +61,6 @@ class ExportModel(nn.Layer):
         return x
 
 
-class IdentityHead(nn.Layer):
-    def __init__(self):
-        super(IdentityHead, self).__init__()
-
-    def forward(self, x, label=None):
-        return {"features": x, "logits": None}
-
-
 if __name__ == "__main__":
     args = config.parse_args()
     config = config.get_config(args.config, overrides=args.override, show=True)