fix(tui): add missing serial_test dev-dependency

The external_editor tests use serial_test for test isolation
but it was missing from the Cargo.toml dependencies.

code-rs/Cargo.lock

@@ -1599,6 +1599,7 @@ dependencies = [
  "serde",
  "serde_bytes",
  "serde_json",
+ "serial_test",
  "sha2",
  "shlex",
  "signal-hook",

code-rs/Cargo.toml

@@ -152,6 +152,7 @@ schemars = "0.8.22"
 seccompiler = "0.5.0"
 serde = "1"
 serde_json = "1"
+serial_test = "3"
 serde_with = "3.14"
 sha1 = "0.10.6"
 sha2 = "0.10"

code-rs/tui/Cargo.toml

@@ -120,6 +120,7 @@ indoc = "2.0"
 insta = "1.43.1"
 pretty_assertions = "1"
 rand = "0.9"
+serial_test = { workspace = true }
 strip-ansi-escapes = "0.1"
 serde_bytes = "0.11"
 code-tui = { path = ".", features = ["test-helpers"] }