Weblate SSRF: outbound URL guard misses some private ranges
### Impact
Weblate's `VCS_RESTRICT_PRIVATE` did not properly account for some transitional IPv6 ranges, multicast addresses, or some semi-private IPv4 ranges, which allowed some addresses to bypass private range restrictions.
### Patches
*
https://github.com/WeblateOrg/weblate/pull/19768
### Resources
The issue was reported by @tonghuaroot via GitHub, and the same user also provided the initial patch.