modify omegaconf version constraint

Author: yunchu

requirements/api.txt

@@ -3,7 +3,7 @@
 attrs==23.1.*
 networkx>=2.6,<=2.8.0
 numpy>=1.21.0,<=1.23.4  # np.bool was removed in 1.24.0 which was used in openvino runtime
-omegaconf==2.3.*
+omegaconf~=2.1.1
 opencv-python==4.8.1.*
 pymongo==4.6.*
 scikit-learn==1.3.*