What did you implement:

Dependency graph API request can be failed for some reason like timeout at busy server time.
so this PR gives chances to retry request up to 3 times, and enhanced error handling a little bit.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

$ vuls report -to-localfile -format-cyclonedx-json
or 
$ vuls report -to-localfile -format-cyclonedx-xml

Retrying on timeout (raised on purpose)

Retrying on bad request (raised on purpose)

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES

Reference

#1642