ocm: update checksum for 1.0.15 release

[stefanb]

Release workflow run history
https://github.com/openshift-online/ocm-cli/actions/workflows/publish-release.yaml

indicates that the tag v1.0.15 was present on two commits:

• first: openshift-online/ocm-cli@a40ce35 by @rcampos2029
• second, where tag is currently: openshift-online/ocm-cli@6003381 also by @rcampos2029

Diff: openshift-online/ocm-cli@a40ce35...6003381 contains just an empty commit with git tag to trigger a release.

Ref:

• https://github.com/openshift-online/ocm-cli/releases/tag/v1.0.15
• ocm 1.0.15 #282788
• go 1.27.0, go@1.26 1.26.7 (new formula) #288803

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