Release v2.15.2

[yhabteab]

This PR prepares the Changelog for the upcoming 2.15.2 release. It's ready to be reviewed but not to be merged yet, as we will bump OpenSSL tomorrow and want to include that in the Changelog as well. Apart from that, everything else is set.

[yhabteab]

Sorry, removed the GHAs related changelog entry, since we never included them in any of the previous releases.

[yhabteab]

It's ready to be reviewed but not to be merged yet, as we will bump OpenSSL tomorrow and want to include that in the Changelog as well.

Done!

[julianbrost]

Just the changelog, not code change, so not worth waiting for all actions. (And we are in a bit of a hurry as the OpenSSL Windows builds came in a bit late.)

The one already failed pipeline is due to a mirror issue, no sign of a problem on our side:

E: Failed to fetch http://deb.debian.org/debian-security/pool/updates/main/p/python3.9/libpython3.9-stdlib_3.9.2-1%2bdeb11u5_amd64.deb  Error reading from server - read (104: Connection reset by peer) [IP: 151.101.42.132 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
Error: Process completed with exit code 100.