check for updates (#1764)

1. Ping https://api.github.com/repos/openai/codex/releases/latest (at
most once every 20 hrs)
2. Store the result in ~/.codex/version.jsonl
3. If CARGO_PKG_VERSION < latest_version, print a message at boot.

---------

Co-authored-by: easong-openai <easong@openai.com>

codex-rs/Cargo.lock

@@ -843,6 +843,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "base64 0.22.1",
+ "chrono",
  "clap",
  "codex-ansi-escape",
  "codex-arg0",
@@ -861,6 +862,8 @@ dependencies = [
  "ratatui",
  "ratatui-image",
  "regex-lite",
+ "reqwest",
+ "serde",
  "serde_json",
  "shlex",
  "strum 0.27.2",