Pre-filter GitHub v1 findings to prevent large numbers of validation requests

[trufflesteeeve]

Description:

GitHub v1 tokens are unlikely, so verifying them should only be done if we're relatively confident that the sha256 hash we're seeing isn't actually a sha256 hash.

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[martinlocklear]

I think this makes a ton of sense. In one perspective, verification is just another way to filter results, and doing the largest amount of culling early makes sense to me.