"for_packages" not populated for Rust package resources

I ran a `scan_single_package` pipeline with pkg:cargo/syn@2.0.117. It correctly returned one detected package. However, none of the corresponding source files in the output include a `for_packages` value. Only `Cargo.toml` and `Cargo.lock` contain a for_packages entry.

The file "Cargo.toml" has the "include" list section that could be used to populate the "for_packages"
e.g.
```
[package]
edition = "2021"
rust-version = "1.71"
name = "syn"
version = "2.0.117"
authors = ["David Tolnay "]
build = false
include = [
"/benches/**",
"/Cargo.toml",
"/LICENSE-APACHE",
"/LICENSE-MIT",
"/README.md",
"/src/**",
"/tests/**",
]
```