CI: 2 ERROR

[Bruno Haible via Bug reports for the GNU Texinfo documentation system]

Today's CI fails because the tests produce 2 ERRORs:

...
PASS: t/epub_tests.t 78 - epub_metadata converted file_epub
PASS: t/epub_tests.t 79 - epub_metadata errors file_epub
ERROR: t/epub_tests.t - missing test plan
ERROR: t/epub_tests.t - exited with status 2
PASS: t/formats_encodings.t 1
PASS: t/formats_encodings.t 2 - documentencoding_utf8_and_insertions tree
...