chore(release): v2.6.0 changes.

date/version label updates.

CHANGES.txt - add rst formatting to prevent strings ending with _ from
    being interpreted as links.

COPYING.txt - add note that vendored cgi.py is not under MIT license

CVE.txt - comment out CVE references allow upgrading.txt references
    to be active.


announcement.txt - clarify supported python versions (3.10+).

security.txt, roundup-2.6.0b1.tar.gz.asc - add gpg detatched signature
    and reference

upgrading.txt, upgrading-history.txt - mobe release 1.5.1 to history.

upgrading.txt - make CVE references live

setup.py - development status production, remove license classifiers,
   remove license metadata add license-expression metadata, space
   formatting fixups, python_requires now >=3.10

index.txt - add entry for PATHC not being CSRF protected
  typo and wording fixups.

chore: release 2.6.0b1

build: 2.5.0 release checkin. Tag to come.

chore: update files for release 2.5.0b1.

docs: add 2.4.0 gpg signature.

2.4.0b1 release commits

Removed tag 2.4.1b1

Removed tag 2.4.0b0

fix: close file properly in indexer_dbm.py:save_index()

Fix this error found in debug logs of gentoo packaging of round 2.2.0.

/roundup/backends/indexer_dbm.py:253: ResourceWarning: unclosed file
<_io.BufferedWriter name='test-index/indexes/index.db-'>
    open(self.indexdb+'-', 'wb').write(zlib.compress(marshal.dumps(dbfil)))

Also added test that calls save_index(), reloads the index and tests
that the original item. I am not sure how Gentoo hit
this But they were missing a number of backends. So it's possible that
indexer_dbm.py is not getting fully tested depending on what is
installed on the system. Codecov from CI didnt show
indexer_dbm.py:save_index() being covered.

Update for 2.3.0 release