CI: Figure out how to store screenshots

[TWiStErRob]

Somehow test report knows master results, figure out how.

[TWiStErRob]

Encrico said/showed there's a marker at the end of each summary:
https://github.com/TWiStErRob/net.twisterrob.sun/actions/runs/6031749294/jobs/11172204869/summary_raw

## 🔔 Test: Unit Results
  16 files  ±0    16 suites  ±0   10s [:stopwatch:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "duration of all tests") -2s
119 tests ±0  111 [:heavy_check_mark:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "passed tests") ±0  8 [:zzz:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "skipped / disabled tests") ±0  0 [:x:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "failed tests") ±0 
193 runs  ±0  185 [:heavy_check_mark:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "passed tests") ±0  8 [:zzz:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "skipped / disabled tests") ±0  0 [:x:](https://github.com/EnricoMi/publish-unit-test-result-action/blob/v2.9.0/README.md#the-symbols "failed tests") ±0 

Results for commit 44848b39. ± Comparison against earlier commit 7ceb0e8a.

but it's not there any more.

[TWiStErRob]

Ah, it's there: https://api.github.com/repos/TWiStErRob/net.twisterrob.sun/check-runs/16366043965