Linux, macOS, or Windows host. Linux supports both the root
privilege-dropping path and the unprivileged path; macOS and Windows support
the unprivileged path.
Rust toolchain specified in rust-toolchain.toml.
Outbound network access to crates.io and the PostgreSQL binary archive.
System timezone database where required. On Unix-like systems, this package is
usually named tzdata; Windows uses the platform timezone database.