Add retries on the `get` request of `get_transform_status` function

[kyungeonchoi]

• Add retries (5 times with 3 sec sleep) on the get request of get_transform_status function
• This can fix the issue #450

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.40%. Comparing base (e681796) to head (5bc0c40). Report is 27 commits behind head on 3.0_develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 3.0_develop #469 +/- ## =============================================== + Coverage 82.32% 83.40% +1.07% =============================================== Files 26 26 Lines 1386 1440 +54 =============================================== + Hits 1141 1201 +60 + Misses 245 239 -6 ``` | [Flag](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/469/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/469/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | `83.40% <100.00%> (+1.07%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.