docs: remove superfluous arg in an example (#1972)

Author: alexandre-daubois

docs/extensions.md

@@ -180,7 +180,7 @@ func process_data_unordered_map(arr *C.zval) unsafe.Pointer {
 // export_php:function process_data_packed(array $input): array
 func process_data_packed(arr *C.zval) unsafe.Pointer {
 	// Convert PHP packed array to Go
-	goSlice, err := frankenphp.GoPackedArray(unsafe.Pointer(arr), false)
+	goSlice, err := frankenphp.GoPackedArray(unsafe.Pointer(arr))
     if err != nil {
         // handle error
     }