Bump docker/build-push-action from 5 to 6 #245

Job	Run time
bookworm armv7 / build	17m 5s
bullseye armv7 / build	17m 34s
bookworm armv7 / test (pi, run_installation_classic.sh)	11m 13s
bookworm armv7 / test (pi, run_installation_rfid.sh)	11m 40s
bookworm armv7 / test (pi, run_installation_spotify.sh)	17m 48s
bookworm armv7 / test (pi, run_installation_staticip_dhcpcd.sh)	11m 45s
bookworm armv7 / test (pi, run_installation_autohotspot_dhcpcd.sh)	12m 14s
bookworm armv7 / test (pi, run_installation_autohotspot_NetworkManager.sh)	12m 2s
bookworm armv7 / test (hans, run_installation_classic.sh)	57s
bullseye armv7 / test (pi, run_installation_classic.sh)	4m 31s
bullseye armv7 / test (pi, run_installation_rfid.sh)	5m 41s
bullseye armv7 / test (pi, run_installation_spotify.sh)	8m 56s
bullseye armv7 / test (pi, run_installation_staticip_dhcpcd.sh)	4m 30s
bullseye armv7 / test (pi, run_installation_autohotspot_dhcpcd.sh)	5m 44s
bullseye armv7 / test (pi, run_installation_autohotspot_NetworkManager.sh)	5m 16s
bullseye armv7 / test (hans, run_installation_classic.sh)	4m 24s
bullseye armv7 / cleanup	3s
bookworm armv7 / cleanup	7s
	2h 31m 30s

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