Migrate to core::error::Error #3712

Job	Run time
features_check (ubuntu-latest)	6m 6s
rust_msrv (ubuntu-latest)	17s
rust_versions (ubuntu-latest, stable)	59s
timezones (ubuntu-latest, ACST-9:30)	1m 10s
rust_versions (ubuntu-latest, beta)	1m 4s
rust_versions (ubuntu-latest, nightly)	51s
timezones (macos-latest, EST4)	40s
timezones (macos-latest, Asia/Katmandu)	45s
timezones (ubuntu-latest, Asia/Katmandu)	1m 15s
timezones (macos-latest, UTC0)	40s
timezones (ubuntu-latest, UTC0)	1m 14s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	18s
timezones (macos-latest, ACST-9:30)	55s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	22s
timezones (ubuntu-latest, EST4)	1m 10s
timezones (windows-latest, Asia/Katmandu)	1m 35s
timezones (windows-latest, UTC0)	1m 43s
alternative_targets (ubuntu-latest, aarch64-linux-android)	22s
timezones (windows-latest, ACST-9:30)	1m 43s
timezones (windows-latest, EST4)	1m 57s
test_wasm (ubuntu-latest)	24s
cross-targets (x86_64-unknown-illumos)	1m 15s
no_std (ubuntu-latest, thumbv6m-none-eabi)	21s
check-docs	21s
cross-tests (ubuntu-latest)	1m 59s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	22s
test_wasip1 (ubuntu-latest, wasm32-wasip1)	18s
	30m 6s

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