Prevent ambigious splitting of [0-9]{4}-[0-9]{2}

src/NodaTimeSplitter.php

@@ -609,6 +609,12 @@ final class NodaTimeSplitter {
 
             // Assume the end is a month
             if (intval($month) < 12) {
+                // If the year is smaller than the second number, do not split, as either month
+                // or year may be meant
+                // Example: 1903-04
+                if (substr($datum, 2, 2) < 12) {
+                    return false;
+                }
                 return new NodaSplitTime($year, $year, $month);
             }
             else {