The per-file JUnit merge was walking `<testsuite>` tags by hand and closing
on the first `</testsuite>` it found. Bun's junit reporter nests one
`<testsuite>` per `describe` block inside an outer `<testsuite>` for the
file itself, so the inner close was matched and the outer one got dropped.
Every file contributed one unclosed `<testsuite>` to the merged output,
pushing XML depth up until mikepenz/action-junit-report's sax parser
failed with "Unexpected close tag" (and xmllint with "Excessive depth").
Switch to grabbing everything between the outer `<testsuites ...>` and
`</testsuites>` of each file's XML — nested structure is preserved
verbatim, no custom walking needed. Read aggregate counts from the root
`<testsuites>` attributes so nested `tests="..."` attrs don't get
double-counted either.
Validated locally: `xmllint --noout` passes on the merged output for a
mix of files with and without nested describes.
Catriel Müller
c21a1b855f