change paddle required version to 1.8.4 (#420)

paddleslim/quant/__init__.py

@@ -15,17 +15,25 @@
 import logging
 
 import paddle.fluid as fluid
+import paddle.version as fluid_version
 from ..common import get_logger
 
 _logger = get_logger(__name__, level=logging.INFO)
 
 try:
-    fluid.require_version('2.0.0')
+    fluid.require_version('1.8.4')
+    version_installed = [
+        fluid_version.major, fluid_version.minor, fluid_version.patch,
+        fluid_version.rc
+    ]
+    assert version_installed != [
+        '2', '0', '0-alpha0', '0'
+    ], "training-aware and post-training quant is not supported in 2.0 alpha version paddle"
     from .quanter import quant_aware, convert, quant_post_static, quant_post_dynamic
     from .quanter import quant_post, quant_post_only_weight
 except Exception as e:
     _logger.warning(
         "If you want to use training-aware and post-training quantization, "
-        "please use Paddle >= 2.0.0 or develop version")
+        "please use Paddle >= 1.8.4 or develop version")
 
 from .quant_embedding import quant_embedding