fix port choice #18

Job	Run time
Homebrew packaging unit tests	6m 44s
C++ unit tests on macos-latest, as root	20m 44s
Node.js unit tests on macos-latest	48s
Apache 2 integration tests on macos-latest	3m 36s
C++ unit tests on ubuntu-latest, as root	6m 36s
Node.js unit tests on ubuntu-latest	50s
Nginx dynamic module integration tests on macos-latest	4m 1s
Source packaging unit tests	55s
C++ unit tests on macos-latest, as normal-user	4m 0s
Ruby unit tests on macos-latest	2m 20s
Nginx integration tests on macos-latest	3m 52s
Ruby unit tests on ubuntu-latest	3m 24s
C++ unit tests on ubuntu-latest, as normal-user	6m 30s
Standalone integration tests on macos-latest	3m 57s
Apache 2 integration tests on ubuntu-latest	4m 39s
Nginx dynamic module integration tests on ubuntu-latest	4m 30s
Nginx integration tests on ubuntu-latest	4m 18s
Standalone integration tests on ubuntu-latest	5m 28s
	1h 27m 12s

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