Fixing ref issue with stable

Author: holtgrewe

src/bcf/mod.rs

@@ -849,8 +849,8 @@ mod tests {
 
         match &records[0] {
             &HeaderRecord::Filter {
-                key,
-                key_value_pairs,
+                ref key,
+                ref key_value_pairs,
             } => {
                 assert_eq!(key, "FILTER");
                 assert_eq!(key_value_pairs[0], ("ID".to_string(), "PASS".to_string()));