Fix V7Fix, should fix crash with older presets

Author: Niko-sk2x

src/main/java/io/github/opencubicchunks/cubicchunks/cubicgen/preset/fixer/V7Fix.java

@@ -35,7 +35,7 @@
 public class V7Fix implements IJsonFix {
 
     private final JsonTransformer<Function<JsonObject, JsonObject>> transformer = JsonTransformer.<Function<JsonObject, JsonObject>>builder("V6 -> V7")
-            .valueTransform("version", (e, ctx) -> new JsonPrimitive(6))
+            .valueTransform("version", (e, ctx) -> new JsonPrimitive(7))
             .passthroughFor(
                     "caves",
                     "strongholds", "alternateStrongholdsPositions",