ci: fix typo in s390x image name

3 jobs for master in 48 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #52
s390x docker-alpine
build-s390x

00:00:13

 
  Upload
passed #53
s390x docker-alpine
upload-s390x

00:00:14

 
  Manifest
passed #54
s390x docker-alpine
create-manifest

00:00:19