Fix code smell (#406)

Author: mfvanek

pg-index-health-model/src/test/java/io/github/mfvanek/pg/model/validation/ValidatorsTest.java

@@ -52,7 +52,7 @@ void validPercentTest() {
             .isEqualTo(50.0);
 
         assertThat(Validators.validPercent(0.0, "remainingPercentageThreshold"))
-            .isEqualTo(0.0);
+            .isZero();
 
         assertThat(Validators.validPercent(100.0, "remainingPercentageThreshold"))
             .isEqualTo(100.0);
@@ -72,7 +72,7 @@ void argumentNotNegative() {
             .isInstanceOf(IllegalArgumentException.class)
             .hasMessage("arg cannot be less than zero");
         assertThat(Validators.argumentNotNegative(0, "arg"))
-            .isEqualTo(0);
+            .isZero();
         assertThat(Validators.argumentNotNegative(11, "arg"))
             .isEqualTo(11);
     }