chore: Refactor DownloadableAsset tests to use httptest instead of a local TcpListener

Cargo.lock

@@ -568,6 +568,21 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82b8f8f868b36967f9606790d1903570de9ceaf870a7bf9fbbd3016d636a2cb2"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
+
 [[package]]
 name = "crossterm"
 version = "0.25.0"
@@ -1544,6 +1559,30 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
 
+[[package]]
+name = "httptest"
+version = "0.16.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bde82de3ef9bd882493c6a5edbc3363ad928925b30ccecc0f2ddeb42601b3021"
+dependencies = [
+ "bstr",
+ "bytes",
+ "crossbeam-channel",
+ "form_urlencoded",
+ "futures",
+ "http 1.3.1",
+ "http-body-util",
+ "hyper 1.6.0",
+ "hyper-util",
+ "log",
+ "once_cell",
+ "regex",
+ "serde",
+ "serde_json",
+ "serde_urlencoded",
+ "tokio",
+]
+
 [[package]]
 name = "hyper"
 version = "0.14.32"
@@ -1581,6 +1620,7 @@ dependencies = [
  "http 1.3.1",
  "http-body 1.0.1",
  "httparse",
+ "httpdate",
  "itoa",
  "pin-project-lite",
  "smallvec",
@@ -2026,6 +2066,7 @@ dependencies = [
  "async-trait",
  "env_logger",
  "futures-util",
+ "httptest",
  "log",
  "octocrab",
  "pretty_assertions",