The checksums listed only *.tar*, so the two ICU source archives the frontends
need (icu4c-78.3-sources.tgz, icu4c-78.3-data.zip) were written without one.
They are now taken from every file the bundle writes, except the index files.
Verified: python3 -m unittest tests.test_source_bundle fails before the change
and passes after it; TMPDIR=$PWD/build/tmp bash tools/verify.sh -> verify: PASS
(format unit build integration evidence); python3 tools/source-bundle.py
dist/PPSA99169 dist/source-v0.6.7-alpha.6 -> 37 archives, 37 SHA256SUMS lines,
sha256sum -c all OK.
