fix: management of undefined billing

Author: Alex-GF

src/main/java/io/github/isagroup/services/parsing/PricingManagerParser.java

@@ -204,6 +204,10 @@ private static void setBasicAttributes(Map<String, Object> yamlConfigMap, Pricin
             }
 
             pricingManager.setBilling(parsedBilling);
+        }else{
+            Map<String, Double> billingMap = new LinkedHashMap<>();
+            billingMap.put("monthly", 1.0);
+            pricingManager.setBilling(billingMap);
         }
 
     }

src/test/java/io/github/isagroup/parsing/positive/PricingManagerParserTest.java

@@ -40,7 +40,6 @@ void givenAMapOfBillingShouldParseIt() {
 
     @Test
     @DisplayName(value = "Given no 'billing' by default should set a 'monthly: 1'")
-    @Disabled
     void givenNoBillingADefaultMonthlyValueShouldBeSet() {
 
         PricingManager pricingManager = YamlUtils.retrieveManagerFromYaml(TEST_CASES + "billing/no-billing-set.yml");
@@ -51,7 +50,6 @@ void givenNoBillingADefaultMonthlyValueShouldBeSet() {
 
     @Test
     @DisplayName(value = "Given a single entry in 'billing' map should parse it")
-    @Disabled
     void givenBillingOneEntryShouldParse() {
 
         PricingManager pricingManager = YamlUtils