Resolve needless_borrowed_reference clippy lints

    error: dereferencing a tuple pattern where every element takes a reference
       --> src/value/de.rs:997:18
        |
    997 |             Some(&Value::Array(ref v)) => {
        |                  ^^^^^^^^^^^^^^^^^^^^
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrowed_reference
        = note: `-D clippy::needless-borrowed-reference` implied by `-D clippy::all`
    help: try removing the `&` and `ref` parts
        |
    997 -             Some(&Value::Array(ref v)) => {
    997 +             Some(Value::Array(v)) => {
        |

    error: dereferencing a tuple pattern where every element takes a reference
        --> src/value/de.rs:1024:18
         |
    1024 |             Some(&Value::Object(ref v)) => visit_object_ref(v, visitor),
         |                  ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrowed_reference
    help: try removing the `&` and `ref` parts
         |
    1024 -             Some(&Value::Object(ref v)) => visit_object_ref(v, visitor),
    1024 +             Some(Value::Object(v)) => visit_object_ref(v, visitor),
         |

src/value/de.rs

@@ -994,7 +994,7 @@ impl<'de> VariantAccess<'de> for VariantRefDeserializer<'de> {
         V: Visitor<'de>,
     {
         match self.value {
-            Some(&Value::Array(ref v)) => {
+            Some(Value::Array(v)) => {
                 if v.is_empty() {
                     visitor.visit_unit()
                 } else {
@@ -1021,7 +1021,7 @@ impl<'de> VariantAccess<'de> for VariantRefDeserializer<'de> {
         V: Visitor<'de>,
     {
         match self.value {
-            Some(&Value::Object(ref v)) => visit_object_ref(v, visitor),
+            Some(Value::Object(v)) => visit_object_ref(v, visitor),
             Some(other) => Err(serde::de::Error::invalid_type(
                 other.unexpected(),
                 &"struct variant",