build(deps): bump docker/build-push-action from 6.7.0 to 6.8.0 #10

Job	Run time
changes	4s
prechecks / validate	36s
prechecks / bootstrap-dev-rhel8	4m 16s
prechecks / style	53s
prechecks / import-check	48s
prechecks / audit / package-audits (windows-latest, powershell Invoke-Expression -Command "./share/spack/qa/windows_t...	2m 31s
prechecks / audit / package-audits (ubuntu-latest, bash)	4m 4s
prechecks / audit / package-audits (macos-latest, bash)	2m 57s
all-prechecks	1s
bootstrap	0s
unit-tests	0s
upload-coverage	0s
all	0s
	16m 10s

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