Enable release mode builds #73

Job	Run time
Construct Cxx interop matrix	5s
Unit tests / Unit tests (5.9)	33s
Unit tests / Unit tests (6.1)	2m 47s
Unit tests / Unit tests (5.10)	3m 56s
Unit tests / Unit tests (nightly-6.1)	2m 55s
Unit tests / Unit tests (nightly-main)	3m 6s
Unit tests / Unit tests (6.0)	2m 55s
Release builds / Release builds (5.10)	2m 5s
Release builds / Release builds (6.1)	1m 52s
Release builds / Release builds (6.0)	1m 55s
Release builds / Release builds (nightly-6.1)	2m 15s
Release builds / Release builds (nightly-main)	2m 19s
Release builds / Release builds (5.9)	23s
Soundness / API breakage check	2m 12s
Soundness / Documentation check	1m 47s
Soundness / YAML lint check	7s
Soundness / Shell check	39s
Soundness / Unacceptable language check	5s
Soundness / License headers check	6s
Soundness / Broken symlinks check	9s
Soundness / Python lint check	7s
Soundness / Format check	33s
Cxx interop / Linux (6.0)	1m 37s
Cxx interop / Linux (5.10)	1m 27s
Cxx interop / Linux (6.1)	1m 36s
Cxx interop / Linux (nightly-main)	1m 51s
Cxx interop / Linux (nightly-next)	2m 0s
	41m 22s

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