vladopajic/go-test-coverage@v2 (v2.18.5+) restructured the composite
action to pass inputs via env-var mapping. Gitea act_runner does not
expand expressions in those blocks, so the literal string
'${{ inputs.config }}' reached the binary, breaking the coverage step.
Replace the action with a direct go install + binary invocation
(matching the Frostmoln pattern) and use --github-action-output to
expose total-coverage as a step output, dropping manual
'go tool cover -func' calculations.