Reset pending changelog after 2.075.0

[wilzbach]

We should probably include this into the release pipeline ...
CC @MartinNowak

[nemanja-boric-sociomantic]

This needs to be pulled in: #1821

[MartinNowak]

Right now I've done it on stable after a release, then purged master when merging back.
https://gist.github.com/MartinNowak/a471fe7ddbfeef205cdf04c93a94c6d0#file-release-sh-L153
That way we only purge things after they've actually been released. Should be fine to have those changelog files still in master for a week to two, no?

[MartinNowak]

Let's stick with that scheme for the moment. Purging changelogs after sth. has been released seems more sound and might turn out necessary if we start to backport fixes at some point.

[CyberShadow]

@MartinNowak The problem with the current approach is that once you create the _pre.dd changelog file on dlang.org master, it becomes impossible to preview any new changelog entries until the pending version is released. Would it be possible to adjust the release workflow to accommodate this?