Change in coreboot[master]: util/gitconfig/test: Add shellcheck test

[build bot (Jenkins) (Code Review)]

build bot (Jenkins) has posted comments on this change. ( https://review.coreboot.org/23283 )

Change subject: util/gitconfig/test: Add shellcheck test
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Patch Set 3: Verified-1

Build Failed

https://qa.coreboot.org/job/coreboot-checkpatch/22746/ : ABORTED

https://qa.coreboot.org/job/coreboot-gerrit/68310/ : ABORTED