PULL_REQUEST_TEMPLATE

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     - "[#255] test: fix flaky test NameOfTheTest"
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### What changes were proposed in this pull request?

(Please outline the changes and how this PR fixes the issue.)

### Why are the changes needed?

(Please clarify why the changes are needed. For instance,
  1. If you propose a new API, clarify the use case for a new API.
  2. If you fix a bug, describe the bug.)

Fix: # (issue)

### Does this PR introduce _any_ user-facing change?

(Please list the user-facing changes introduced by your change, including
  1. Change in user-facing APIs.
  2. Addition or removal of property keys.)

### How was this patch tested?

(Please test your changes, and provide instructions on how to test it:
  1. If you add a feature or fix a bug, add a test to cover your changes.
  2. If you fix a flaky test, repeat it for many times to prove it works.)