403 Forbidden on Docker build

[chrisfenner]

Example run: https://github.com/TrustedComputingGroup/pandoc/actions/runs/15000557158/job/42146104473?pr=232

#45 exporting to image
#45 pushing layers 0.6s done
#45 ERROR: failed to push ghcr.io/trustedcomputinggroup/pandoc_test:latest: unexpected status from POST request to https://ghcr.io/v2/trustedcomputinggroup/pandoc_test/blobs/uploads/: 403 Forbidden
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 > exporting to image:
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ERROR: failed to solve: failed to push ghcr.io/trustedcomputinggroup/pandoc_test:latest: unexpected status from POST request to https://ghcr.io/v2/trustedcomputinggroup/pandoc_test/blobs/uploads/: 403 Forbidden
Reference
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