fix(content): Clear the tribute fleet from Kort Vek'kri once it changes governments (endless-sky#10738)

Author: TheGiraffe3

data/wanderer/wanderers start.txt

@@ -2457,6 +2457,21 @@ event "battle for sich'ka'ara ends"
 	planet "Kort Vek'kri"
 		attributes "unfettered"
 		spaceport `The Unfettered clearly do not know quite what to make of the Wanderer research station here that they have recently captured. Animals that were once part of various experiments are now wandering loose, and the Unfettered are making only sporadic efforts to keep them well-fed. Every once in a while one of them, driven by sheer hunger, tries to smash its way into one of the crates of military rations that the Unfettered have stacked up in the shade near the main landing pad.`
+		remove tribute
+
+# Patch mission for players who got these missions before 0.10.11 and didn't get tribute from Kort Vek'kri cleared.
+mission "Wanderers: Kort Vek'kri Tribute Patch"
+	landing
+	invisible
+	to offer
+		has "event: battle for sich'ka'ara ends"
+	on offer
+		event "kort vek'kri tribute clear"
+		fail
+
+event "kort vek'kri tribute clear"
+	planet "Kort Vek'kri"
+		remove tribute
 
 event "solifuge deployment"
 	shipyard "Mon Ki o'Uden Advanced"

data/wanderer/wanderers.txt

@@ -878,6 +878,7 @@ event "wanderers: more systems lost"
 		attributes "unfettered" "fishing"
 		description `The surface of this world is almost entirely ocean. The Wanderer settlements were built on massive floating algae mats, some of them the size of a small city. Engines are attached to some of these floating villages, allowing them to be slowly propelled from one part of the planet's surface to another, and the only native industries are fishing and seaweed farming.`
 		spaceport `The raft of algae that supports the spaceport is probably at least a dozen meters thick, but flexible enough that it bends as the ocean swells pass underneath, causing individual buildings to rise up or tilt slightly relative to their neighbors. Now that this world has been captured by the Unfettered, nearly all the buildings are empty; it appears that the Hai are not too fond of the idea of inhabiting a water world, so they are using it mostly as a military base.`
+		remove tribute
 
 planet "The Eye"
 	spaceport ""