Add back datetime imports

Author: AdrienVannson

src/betterproto/plugin/models.py

@@ -440,15 +440,14 @@ def betterproto_field_args(self) -> List[str]:
 
     @property
     def datetime_imports(self) -> Set[str]:
-        # imports = set()
-        # annotation = self.annotation
-        # # FIXME: false positives - e.g. `MyDatetimedelta`
-        # if "timedelta" in annotation:
-        #     imports.add("timedelta")
-        # if "datetime" in annotation:
-        #     imports.add("datetime")
-        # return imports
-        return {"timedelta", "datetime"}
+        imports = set()
+        annotation = self.annotation
+        # FIXME: false positives - e.g. `MyDatetimedelta`
+        if "timedelta" in annotation:
+            imports.add("timedelta")
+        if "datetime" in annotation:
+            imports.add("datetime")
+        return imports
 
     @property
     def pydantic_imports(self) -> Set[str]: