[App][CI] Fix psutil requirement CI

[manskx]

What does this PR do?

Fixing this error in running CI tests

ImportError while loading conftest '/home/runner/work/lightning/lightning/tests/tests_app/conftest.py'.
tests_app/conftest.py:7: in <module>
    import psutil
E   ModuleNotFoundError: No module named 'psutil'

Fixes #<issue_number>

Does your PR introduce any breaking changes? If yes, please list them.

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cc @carmocca @akihironitta @Borda

[rohitgr7]

qq: why was it marked as all:next? since it only touches the app.

[Borda]

qq: why was it marked as all:next? since it only touches the app.

fixed, shall go to App :)