update site tier enum name to fit naming scheme

gso/products/product_blocks/site.py

@@ -5,10 +5,10 @@ from orchestrator.types import SubscriptionLifecycle, strEnum
 
 
 class SiteTier(strEnum):
-    tier1 = 1
-    tier2 = 2
-    tier3 = 3
-    tier4 = 4
+    TIER1 = 1
+    TIER2 = 2
+    TIER3 = 3
+    TIER4 = 4
 
 
 class SiteBlockInactive(ProductBlockModel, lifecycle=[SubscriptionLifecycle.INITIAL], product_block_name="SiteBlock"):