There's a closed pull request on the void-packages repository

freeciv: Use proper URLs
https://github.com/void-linux/void-packages/pull/41680

Description:
- https instead of http
- Use canonical freeciv wiki URL

Also add a TODO -comment about the need to switch from mostly deprecated gtk3-client to gtk3.22-client.

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>

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#### Testing the changes
- I tested the changes in this PR: **YES**|**briefly**|**NO**

NO: I don't have void-linux installation do to any testing, but the change does not touch any functionality.