#9 Fix subsumption check for strings

If the to be subsumed rule is "not" and the subsuming rule is not not,
then there is never a subsumption.

dmnverifierapi/src/main/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringSubsumes.java

@@ -48,7 +48,7 @@ public class CheckStringSubsumes extends AbstractBoundaryCheck<StringBoundary> {
     if (b1.matchesAny() && !b2.matchesAny()) {
       return true;
     }
-    if (b2.matchesAny()) {
+    if (b2.matchesAny() || !b1.matchesNoneOfValues() && b2.matchesNoneOfValues()) {
       return false;
     }
     int[] b1h = b1.getValuesHashes();