GHA: use nightly toolchain directly in coverage CI job (#1368)
#4623
| Job | Run time |
|---|---|
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| 2m 29s | |
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| 2m 45s | |
| 14s | |
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| 2m 33s | |
| 1m 54s | |
| 4m 29s | |
| 6m 17s | |
| 12m 45s | |
| 4m 40s | |
| 3m 0s | |
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| 10m 17s | |
| 6m 22s | |
| 4m 42s | |
| 1h 16m 27s |