Bump codecov/codecov-action from 4 to 5 #1636

Job	Run time
Build rustls-cert-gen as a standalone package	29s
build-windows	11m 57s
build (macOS-latest, stable)	6m 8s
Validate external types appearing in public API	1m 37s
build (ubuntu-latest, stable)	5m 45s
Measure coverage	5m 59s
build (ubuntu-latest, beta)	5m 47s
Format & clippy	5m 35s
build (ubuntu-latest, nightly)	5m 44s
Documentation (stable)	57s
build (ubuntu-latest, stable 7 months ago)	5m 48s
Check semver compatibility	52s
Documentation (nightly)	1m 4s
	57m 42s

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