clearlydefined requests need a rate limit or backoff

[kpreid]

Today while running my build which includes a cargo about generate I got a flood of warnings like:

2023-02-14 16:24:17.131075 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.134912 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.138537 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.138705 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.147567 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.153689 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.154867 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.155505 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.156357 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.159223 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.159581 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
2023-02-14 16:24:17.160625 +00:00:00 [WARN] failed to request license information from clearly defined: HTTP status: 429 Too Many Requests
...

It seems that cargo-about is making requests too rapidly and needs to implement a rate limit or backoff/retry policy.

It would also be nice if cargo-about documented that it was using a network service by default — I wasn't aware until now that it was.