fix(generator): don't truncate datetime field precision

closes RobertCraigie#804

- [ ] Unit tests for the changes exist
- [ ] Tests pass without significant drop in coverage
- [ ] Documentation reflects changes where applicable
- [ ] Test snapshots have been
[updated](https://prisma-client-py.readthedocs.io/en/latest/contributing/contributing/#snapshot-tests)
if applicable

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src/prisma/generator/templates/builder.py.jinja

@@ -810,9 +810,6 @@ def serialize_datetime(dt: datetime.datetime) -> str:
     elif dt.tzinfo != timezone.utc:
         dt = dt.astimezone(timezone.utc)
 
-    # truncate microseconds to 3 decimal places
-    # https://github.com/RobertCraigie/prisma-client-py/issues/129
-    dt = dt.replace(microsecond=int(dt.microsecond / 1000) * 1000)
     return dt.isoformat()