Make anyhow an optional build-dependency

The `anyhow` dependency is only used if `download` is enabled, same as
all the other optional `build-dependencies`.

Author: tcharding

node/Cargo.toml

@@ -24,12 +24,12 @@ serde_json = { version = "1.0.117" }
 env_logger = "0.9.0"
 
 [build-dependencies]
+anyhow = { version = "1.0.66", optional = true }
 bitcoin_hashes = { version = ">= 0.13, <= 0.14", optional = true }
 flate2 = { version = "1.0", optional = true }
 tar = { version = "0.4", optional = true }
 minreq = { version = "2.9.1", default-features = false, features = ["https"], optional = true }
 zip = { version = "0.6", optional = true }
-anyhow = "1.0.66"
 
 # Please note, in this crate the version features are mutally exclusive.
 #