cargo-about ignores system SSL certificates

[arvid-norlander]

Describe the bug I'm behind a corporate proxy, specifically a transparent HTTPS proxy. This means I need to have a CA certificate installed, but I don't need to set any environment variables. cargo-about seems to ignore the SSL certificates in /etc/ssl/certs

To Reproduce Steps to reproduce the behavior:

1. Be behind a HTTPS proxy
2. Run cargo about generate about.hbs
3. See warnings

2023-11-21 15:18:13.142344125 +00:00:00 [WARN] failed to request license information from clearly defined: error sending request for url (https://api.clearlydefined.io/definitions): error trying to connect: invalid peer certificate: UnknownIssuer
2023-11-21 15:18:13.143837193 +00:00:00 [WARN] failed to request license information from clearly defined: error sending request for url (https://api.clearlydefined.io/definitions): error trying to connect: invalid peer certificate: UnknownIssuer
2023-11-21 15:18:13.144103949 +00:00:00 [WARN] failed to request license information from clearly defined: error sending request for url (https://api.clearlydefined.io/definitions): error trying to connect: invalid peer certificate: UnknownIssuer
[and so on]

Expected behavior cargo-about should respect CA certificates from the system.

Device:

• OS: Ubuntu 22.04 LTS
• Version: cargo-about 0.5.7
• Built with cargo install --locked
• rustc 1.74.0 (79e9716c9 2023-11-13)

Additional context Add any other context about the problem here.