CI: Fix how we supply the codecov token #2874

Job	Run time
rust_msrv (ubuntu-latest)	1m 14s
features_check (ubuntu-latest)	5m 31s
rust_versions (ubuntu-latest, stable)	59s
features_check (macos-latest)	12m 12s
rust_versions (ubuntu-latest, beta)	1m 7s
features_check (windows-latest)	8m 54s
timezones (ubuntu-latest, ACST-9:30)	1m 31s
rust_versions (ubuntu-latest, nightly)	1m 26s
timezones (ubuntu-latest, EST4)	1m 17s
timezones (ubuntu-latest, UTC0)	1m 16s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	16s
timezones (ubuntu-latest, Asia/Katmandu)	1m 27s
check-docs	20s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	14s
alternative_targets (ubuntu-latest, aarch64-linux-android)	9s
timezones (macos-latest, ACST-9:30)	1m 17s
cross-targets (x86_64-sun-solaris)	1m 12s
timezones (macos-latest, EST4)	1m 28s
timezones (macos-latest, UTC0)	57s
timezones (macos-latest, Asia/Katmandu)	1m 49s
cross-tests (ubuntu-latest)	1m 49s
no_std (ubuntu-latest, thumbv6m-none-eabi)	9s
timezones (windows-latest, ACST-9:30)	2m 17s
timezones (windows-latest, EST4)	2m 24s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	16s
test_wasi (ubuntu-latest, wasm32-wasi)	21s
timezones (windows-latest, UTC0)	2m 3s
timezones (windows-latest, Asia/Katmandu)	1m 30s
test_wasm (ubuntu-latest)	24s
	55m 49s

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