set clippy to ignore internal mutability (#7)

Author: matth2k

clippy.toml

@@ -0,0 +1,3 @@
+# prevents a false-positive lint on our types containing bytes::Bytes
+# https://rust-lang.github.io/rust-clippy/master/index.html#/mutable_key_type
+ignore-interior-mutability = ["bytes::Bytes", "circuit::netlist::NetRef"]

src/graph.rs

@@ -70,7 +70,6 @@ where
 {
     fn build(netlist: &'a Netlist<I>) -> Result<Self, String> {
         let mut net_fan_out: HashMap<Net, Vec<NetRef<I>>> = HashMap::new();
-        #[allow(clippy::mutable_key_type)]
         let mut node_fan_out: HashMap<NetRef<I>, Vec<NetRef<I>>> = HashMap::new();
         let mut is_an_output: HashSet<Net> = HashSet::new();
 
@@ -139,7 +138,6 @@ where
     I: Instantiable,
 {
     fn build(netlist: &'a Netlist<I>) -> Result<Self, String> {
-        #[allow(clippy::mutable_key_type)]
         let mut comb_depth: HashMap<NetRef<I>, usize> = HashMap::new();
 
         let mut nodes = Vec::new();