chore: bump provider version used in test (#261)

Author: Ak-sky

tests/resources/existing-resources/instances/version.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     ibm = {
       source  = "ibm-cloud/ibm"
-      version = ">= 1.71.3"
+      version = ">= 1.76.0"
     }
   }
 }