Missing changelog for 6.29.4 and 6.29.5

[frenzymadness]

The subject says it all – the changelog does not cover the last two releases.

[ianthomas23]

@frenzymadness Thanks for reporting this. There have been some problems with the automated CI workflow forward porting changes from the 6.x branch to main which I think are fixed now. Anyway, PR #1263 updates the changelog.