Bump phpunit/phpunit from 9.6.13 to 9.6.15 #91

Job	Run time
buster / build	19m 43s
bullseye / build	20m 10s
bookworm / build	19m 35s
bookworm / test (pi, run_installation_tests.sh)	2m 43s
bookworm / test (pi, run_installation_tests2.sh)	2m 56s
bookworm / test (pi, run_installation_tests3.sh)	3m 30s
bookworm / test (hans, run_installation_tests.sh)	51s
bookworm / test (hans, run_installation_tests2.sh)	1m 0s
bookworm / test (hans, run_installation_tests3.sh)	1m 4s
buster / test (pi, run_installation_tests.sh)	3m 11s
buster / test (pi, run_installation_tests2.sh)	2m 58s
buster / test (pi, run_installation_tests3.sh)	3m 43s
buster / test (hans, run_installation_tests.sh)	54s
buster / test (hans, run_installation_tests2.sh)	54s
buster / test (hans, run_installation_tests3.sh)	55s
bullseye / test (pi, run_installation_tests.sh)	3m 20s
bullseye / test (pi, run_installation_tests2.sh)	3m 13s
bullseye / test (pi, run_installation_tests3.sh)	3m 57s
bullseye / test (hans, run_installation_tests.sh)	1m 5s
bullseye / test (hans, run_installation_tests2.sh)	1m 24s
bullseye / test (hans, run_installation_tests3.sh)	1m 16s
bookworm / cleanup	0s
buster / cleanup	0s
bullseye / cleanup	0s
	1h 38m 22s

Provide feedback