Use compact_rc (#139)

There is not much use for weak_counts in Rc for us.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/value.rs

@@ -8,7 +8,6 @@ use std::collections::{BTreeMap, BTreeSet};
 use std::convert::AsRef;
 use std::ops;
 use std::path::Path;
-use std::rc::Rc;
 use std::str::FromStr;
 
 use anyhow::{anyhow, bail, Result};
@@ -16,6 +15,8 @@ use serde::de::{self, Deserializer, MapAccess, SeqAccess, Visitor};
 use serde::ser::{SerializeMap, Serializer};
 use serde::{Deserialize, Serialize};
 
+pub type Rc<T> = compact_rc::Rc16<T>;
+
 /// A value in a Rego document.
 ///
 /// Value is similar to a [`serde_json::value::Value`], but has the following additional