Bumps _SOULSYNC_BASE_VERSION to 2.7.5, defaults the docker-publish workflow's
version_tag to 2.7.5, and refreshes the release notes for the fixes/features
since 2.7.4: deezer real track numbers, special-edition cover art (release-scope),
the leading-'The' dedup, HiFi preview rejection (#895), M3U/M3U8 import (#893),
organize-by-playlist file naming, durable Find & Add match, ignore-list management
+ manual-add unblock (#897), and the Unraid template fixes (#899). WHATS_NEW +
VERSION_MODAL_SECTIONS rolled to 2.7.5 with 2.7.4 folded into the earlier-versions recap.
ad0eda3575