Impl `From` for a reference type correctly

The previous implementation called `into` on a reference without
dereferencing it. I thought the compiler would implicitly dereference,
but it didn't, which lead to infinite recursion since the fn ended up
calling itself.

zebra-chain/src/primitives/address.rs

@@ -193,6 +193,6 @@ impl From<NetworkKind> for zcash_address::Network {
 
 impl From<&NetworkKind> for zcash_address::Network {
     fn from(network: &NetworkKind) -> Self {
-        network.into()
+        (*network).into()
     }
 }