Use `openssl@3` when building on macOS #61

Job	Run time
Construct Cxx interop matrix	3s
Unit tests / Unit tests (5.9)	4m 1s
Unit tests / Unit tests (5.10)	3m 55s
Unit tests / Unit tests (6.0)	2m 56s
Unit tests / Unit tests (6.1)	2m 55s
Unit tests / Unit tests (nightly-6.1)	3m 8s
Unit tests / Unit tests (nightly-main)	3m 17s
Soundness / API breakage check	1m 31s
Soundness / Unacceptable language check	5s
Soundness / License headers check	6s
Soundness / Documentation check	1m 31s
Soundness / Broken symlinks check	7s
Soundness / Python lint check	8s
Soundness / Format check	37s
Soundness / Shell check	37s
Soundness / YAML lint check	4s
Cxx interop / Linux (5.9)	1m 22s
Cxx interop / Linux (5.10)	1m 22s
Cxx interop / Linux (6.0)	1m 40s
Cxx interop / Linux (6.1)	1m 41s
Cxx interop / Linux (nightly-next)	1m 45s
Cxx interop / Linux (nightly-main)	1m 44s
	34m 35s

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