expliciitly implement SecretsChanged

Author: brettsam

src/WebJobs.Script.WebHost/Security/KeyManagement/ContainerAppsSecretsRepository.cs

@@ -30,7 +30,12 @@ public ContainerAppsSecretsRepository(ILogger<ContainerAppsSecretsRepository> lo
         _logger = logger;
     }
 
-    public event EventHandler<SecretsChangedEventArgs> SecretsChanged;
+    // explicitly implementing this to avoid "unused" warnings on build
+    event EventHandler<SecretsChangedEventArgs> ISecretsRepository.SecretsChanged
+    {
+        add { }
+        remove { }
+    }
 
     public bool IsEncryptionSupported => false;