Add log_config.json to MANIFEST.in (NVIDIA#3166)

Fixes [2332](https://jirasw.nvidia.com/browse/FLARE-2332)

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Quick tests passed locally by running `./runtest.sh`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated.

Co-authored-by: Ziyue Xu <[email protected]>

MANIFEST.in

@@ -2,3 +2,4 @@ include versioneer.py
 include nvflare/_version.py
 include nvflare/libs/*.so
 include nvflare/fuel/utils/*.json
+include nvflare/private/fed/app/simulator/log_config.json