Change threshold in 01_PW/208_PW_CG_float

[19hello]

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[Copilot]

Pull request overview

Updates the per-case numerical tolerance for the single-precision (float) plane-wave CG integration test to better reflect expected precision limits in that configuration.

Changes:

• Adjusted the threshold value for tests/01_PW/208_PW_CG_float from 1e-5 to 2e-5.

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[mohanchen]

Fix #7233