Add grpcio-reflection back to pyfunc server dependencies (#486)

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**What this PR does / why we need it**:
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Follow up from #485

`grpcio-reflection` is needed as a dependency for the Pyfunc UPI server.
Adding it back, without pinning the version.

**Which issue(s) this PR fixes**:
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Fixes #

**Does this PR introduce a user-facing change?**:
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```release-note
Fix: Add back grpcio-reflection as a dependency
```

**Checklist**

- [ ] Added unit test, integration, and/or e2e tests
- [ ] Tested locally
- [ ] Updated documentation
- [ ] Update Swagger spec if the PR introduce API changes
- [ ] Regenerated Golang and Python client if the PR introduce API
changes

python/pyfunc-server/requirements.txt

@@ -7,4 +7,6 @@ uvloop>=0.15.2,<0.18.0
 orjson>=2.6.8
 tornado
 caraml-upi-protos
+grpcio-reflection
+grpcio-health-checking
 file:${SDK_PATH}#egg=merlin-sdk