WIP: Update the hashes dependency to v0.13

This is WIP because we need a branch with this change so we can depend
on it to build `bitcoin` while updating the `hashes` dependency there.

Update to the soon-to-be-released version of `hashes`. This version uses
the soon-to-be-released version of `internals` so we add a patch section
to the manifest which should be removed once we release the new version
of `internals`.

Cargo.toml

@@ -41,7 +41,7 @@ serde = { version = "1.0.103", default-features = false, optional = true }
 
 # You likely only want to enable these if you explicitly do not want to use "std", otherwise enable
 # the respective -std feature e.g., bitcoin-hashes-std
-bitcoin_hashes = { version = "0.12", default-features = false, optional = true }
+bitcoin_hashes = { version = "0.13", default-features = false, optional = true }
 rand = { version = "0.8", default-features = false, optional = true }
 
 [dev-dependencies]
@@ -70,3 +70,7 @@ required-features = ["rand-std"]
 [workspace]
 members = ["secp256k1-sys"]
 exclude = ["no_std_test"]
+
+[patch.crates-io.bitcoin_hashes]
+git = "https://github.com/tcharding/rust-bitcoin"
+branch = "06-20-hashes-release"