fixup! Properly port [modify_side] to Lua

src/scripting/game_lua_kernel.cpp

@@ -2858,7 +2858,7 @@ int game_lua_kernel::intf_set_side_id(lua_State *L)
 	if(flag.empty() && color.empty()) {
 		return 0;
 	}
-	if(team_i < 0 || team_i >= teams().size()) {
+	if(team_i < 0 || static_cast<size_t>(team_i) >= teams().size()) {
 		return luaL_error(L, "set_side_id: side number %d out of range", team_i);
 	}
 	team& side = teams()[team_i];