Disable flaky tests

[pyby]

Description

Following investigation #7, the CI for now can't passed all UserObjectTestCase tests. Maintenance strategy is to run it locally.

Changes made

• Disable flaky tests listed in #7.
• Add Github Pull request template and mentioned to run tests locally.

Checklist

• The branch should be rebased onto the develop branch for whole tests.
• [x] APIs have been properly documented (if relevant).
• [x] The documentation has been updated (if relevant).
• [x] New unit tests have been written (if relevant).
• [x] All UserObjectTestCase tests has passed successfully locally, included flacky disabled ones.
• [x] The demo has been updated (if relevant).
• [x] Issues are linked to the PR, if any.