Release script should be able to handle different changelog format

[arnowelzel]

PR https://github.com/jhass/nextcloud-keeweb/pull/187 suggested a new format for the changelog.

However the release script at https://github.com/jhass/nextcloud-keeweb/blob/master/bin/release seems not to be able to use this format. We need to investigate what is wrong here as the new changelog format should be used.