Update base.py (#232)

Author: tpoisonooo

ppq/quantization/quantizer/base.py

@@ -96,7 +96,7 @@ def quantize_operations(
                 operation_platforms[op_name] = self.target_platform
             else: operation_platforms[op_name] = self.default_platform
 
-            # maunnl override.
+            # manual override.
             if op_name in operation_platforms:
                 operation.platform = operation_platforms[op_name]