test: Add CVE mapping test for GnuTLS 3.8.0

[tutou2356]

1.This PR adds a new CVE mapping test for GnuTLS 3.8.0 in test/test_data/gnutls.py, as part of the "Adding new tests: CVE mapping tests" task. The new test case includes:

{
    "product": "gnutls",
    "version": "3.8.0",
    "version_strings": ["gnutls-cli 3.8.0", "gnutls-serv 3.8.0", "GnuTLS 3.8.0"]
}
2.I ran the tests, all tests passed, including the new gnutls-3.8.0 test case. Here is the test result screenshot:
![test-pass-picture](https://github.com/user-attachments/assets/68711fd8-8b3d-4e71-bbc6-7a0adbebfdef)

[terriko]

The issue with the other test has been resolved so I'm updating this branch to see if this works, but I forgot to edit the title first so it'll fail gitlint.

[terriko]

Okay, looks like we're good to merge now. Thank you!