Relax the assertion for used colors

Author: vnickolov

algo/src/test/java/org/neo4j/gds/beta/k1coloring/K1ColoringTest.java

@@ -136,8 +136,8 @@ void testParallelK1Coloring() {
             .isLessThan(20L);
 
         assertThat(usedColors.size())
-            .as("Used colors should be less than 20")
-            .isLessThan(20);
+            .as("Used colors should be less than or equal to 20")
+            .isLessThanOrEqualTo(20);
     }