Declare targets listed in the build_data attribute of the cargo_build_script rule as prerequisites

[jameseidson]

Here's the relevant code:

cargo_build_script(
    name = ["my-rule"],
    srcs = ["build.rs"],
    build_data = ["//targets:my-target"],
    build_script_env = {
        "TARGET": "$(rootpath //targets:my-target)",
    },
)

When I compile, I get the following error:
<...> in cargo_build_script rule //src:my-rule: label '//targets:my-target' in $(location) expression is not a declared prerequisite of this rule

I'm on version 0.40.0