Remove lightning dependency in unit tests

[zhiqwang]

Seems the version of protobuf Lightning depends on is too old

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[codecov[bot]]

Codecov Report

Base: 98.58% // Head: 92.10% // Decreases project coverage by -6.48% :warning:

Coverage data is based on head (d63b23a) compared to base (1043ee3). Patch coverage: 41.66% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #473 +/- ## ========================================== - Coverage 98.58% 92.10% -6.49% ========================================== Files 11 11 Lines 778 785 +7 ========================================== - Hits 767 723 -44 - Misses 11 62 +51 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `92.10% <41.66%> (-6.49%)` | :arrow_down: | 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=Zhiqiang+Wang#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/zhiqwang/yolov5-rt-stack/pull/473?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang) | Coverage Δ | | |---|---|---| | [test/test\_utils.py](https://codecov.io/gh/zhiqwang/yolov5-rt-stack/pull/473/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang#diff-dGVzdC90ZXN0X3V0aWxzLnB5) | `100.00% <ø> (ø)` | | | [test/test\_trainer.py](https://codecov.io/gh/zhiqwang/yolov5-rt-stack/pull/473/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang#diff-dGVzdC90ZXN0X3RyYWluZXIucHk=) | `25.00% <28.57%> (-75.00%)` | :arrow_down: | | [test/test\_models\_yolov5.py](https://codecov.io/gh/zhiqwang/yolov5-rt-stack/pull/473/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang#diff-dGVzdC90ZXN0X21vZGVsc195b2xvdjUucHk=) | `90.08% <50.00%> (-9.92%)` | :arrow_down: | | [test/test\_data\_pipeline.py](https://codecov.io/gh/zhiqwang/yolov5-rt-stack/pull/473/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang#diff-dGVzdC90ZXN0X2RhdGFfcGlwZWxpbmUucHk=) | `72.72% <66.66%> (-27.28%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Zhiqiang+Wang)

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