It turns out that GetCallerIdentity returns a surprising quantity of transient, false-negative 403 responses that carry the SignatureDoesNotMatch error reason. I don't know why this is happening, but their transient nature makes them indeterminate verification failures and they should be flagged as such. The AWS detector has therefore been modified to specifically look for the InvalidClientTokenId error reason in 403 responses and mark all other responses as indeterminate.
In addition to the functional changes this PR contains some updates to the test code that allow us to test them.
* Adding missing flags to Readme
* Use retryableHttpClient by default for GitHub
* Adding repoUrl for scanning time log
* Use WithField instead of WithFields
* Updating README with lasted --help output
Cody Rose