Fix CHANGELOG for release that didn't occur (#2101)

The original v345 release (prepared in #2095) never ended up being published (I forgot to run the final `make publish` step), and so was superseded by #2100 - which resulted in two v345 entries being present in CHANGELOG.

Signed-off-by: Ed Morley <501702+edmorley@users.noreply.github.com>

Author: edmorley

CHANGELOG.md

@@ -8,9 +8,6 @@
 - Updated pip from 26.1.1 to 26.1.2. ([#2098](https://github.com/heroku/heroku-buildpack-python/pull/2098))
 - Updated Poetry from 2.4.0 to 2.4.1. ([#2098](https://github.com/heroku/heroku-buildpack-python/pull/2098))
 - Updated uv from 0.11.11 to 0.11.19. ([#2098](https://github.com/heroku/heroku-buildpack-python/pull/2098))
-
-## [v345] - 2026-05-11
-
 - The Python 3.14 version alias now resolves to Python 3.14.5. ([#2094](https://github.com/heroku/heroku-buildpack-python/pull/2094))
 
 ## [v344] - 2026-05-07
@@ -1542,7 +1539,6 @@ Default Python is now latest 2.7.10. Updated pip and Distribute.
 
 [unreleased]: https://github.com/heroku/heroku-buildpack-python/compare/v345...main
 [v345]: https://github.com/heroku/heroku-buildpack-python/compare/v344...v345
-[v345]: https://github.com/heroku/heroku-buildpack-python/compare/v344...v345
 [v344]: https://github.com/heroku/heroku-buildpack-python/compare/v343...v344
 [v343]: https://github.com/heroku/heroku-buildpack-python/compare/v342...v343
 [v342]: https://github.com/heroku/heroku-buildpack-python/compare/v341...v342