simple-git: `VISUAL` editor environment variable is omitted from unsafe editor detection

simple-git, an interface for running git commands in any node.js application, enables applications to execute Git operations from JavaScript. Prior to 2.0.1 of the argv-parser package, parseEnv omits VISUAL from GitEnvKeys, so prepareEnv drops the value before vulnerabilityCheck can classify it as allowUnsafeEditor. A consuming application that forwards attacker-influenced environment values can therefore allow Git to invoke an attacker-selected editor during operations such as commit amendment or interactive rebase when no higher-priority editor setting overrides VISUAL and Git's terminal prerequisites are met. The executable runs with the privileges of the Node.js process. This issue is fixed in argv-parser 2.0.1.