Fix parsing for zone offset seconds #3521

Job	Run time
features_check (ubuntu-latest)	3m 45s
no_std (ubuntu-latest, thumbv6m-none-eabi)	9s
rust_msrv (ubuntu-latest)	2m 59s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	14s
rust_versions (ubuntu-latest, stable)	1m 0s
rust_versions (ubuntu-latest, beta)	1m 12s
rust_versions (ubuntu-latest, nightly)	53s
test_wasm (ubuntu-latest)	27s
timezones (ubuntu-latest, ACST-9:30)	1m 20s
timezones (ubuntu-latest, EST4)	1m 25s
timezones (ubuntu-latest, UTC0)	1m 34s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	13s
timezones (ubuntu-latest, Asia/Katmandu)	1m 24s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	17s
check-docs	22s
timezones (macos-latest, ACST-9:30)	34s
alternative_targets (ubuntu-latest, aarch64-linux-android)	9s
timezones (macos-latest, EST4)	33s
cross-targets (x86_64-unknown-illumos)	1m 9s
timezones (macos-latest, UTC0)	34s
timezones (macos-latest, Asia/Katmandu)	32s
cross-tests (ubuntu-latest)	1m 52s
timezones (windows-latest, ACST-9:30)	2m 51s
test_wasi (ubuntu-latest, wasm32-wasi)	25s
timezones (windows-latest, EST4)	1m 26s
timezones (windows-latest, UTC0)	3m 8s
timezones (windows-latest, Asia/Katmandu)	3m 14s
	33m 41s

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