Fix integration tests - revert g_km snapshot test

[edelarua]

✖ | 1       6 | g_km [3.7s]                                                     
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  Failure ('test-g_km.R:50:3'): g_km plot with < = > in group labels works
  Snapshot of `testcase` to 'g_km/grob-tmp-char.svg' has changed
  * Download and unzip run artifact
  * Copy 'tests/testthat/_snaps/g_km/grob-tmp-char.new.svg' to local test directory
  * Run `testthat::snapshot_review('g_km/')` to review changes
  Backtrace:
      ▆
   1. └─vdiffr::expect_doppelganger(title = "grob_tmp_char", fig = grob_tmp_char) at test-g_km.R:50:2
   2.   ├─base::withCallingHandlers(...)
   3.   └─testthat::expect_snapshot_file(...)
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