Update mappings submodule

Author: Camotoy

.gitmodules

@@ -1,3 +1,4 @@
 [submodule "connector/src/main/resources/mappings"]
 	path = connector/src/main/resources/mappings
-	url = https://github.com/GeyserMC/mappings.git
+	url = https://github.com/DoctorMacc/mappings.git
+    branch = mappings-prerelease