chore: prepare release v4.2.0-beta
chore: prepare release v4.2.0-beta

mihailim/epubcheck,w3c/epubcheck,mihailim/epubcheck,IDPF/epubcheck,IDPF/epubcheck,mihailim/epubcheck,IDPF/epubcheck,w3c/epubcheck,mihailim/epubcheck,mihailim/epubcheck,IDPF/epubcheck,w3c/epubcheck,IDPF/epubcheck