fix(deps): update module google.golang.org/protobuf to v1.36.6

Author: renovate[bot]

flagd/go.mod

@@ -29,7 +29,7 @@ require (
 	golang.org/x/net v0.35.0
 	golang.org/x/sync v0.11.0
 	google.golang.org/grpc v1.71.0
-	google.golang.org/protobuf v1.36.5
+	google.golang.org/protobuf v1.36.6
 )
 
 require (