fix: remove duplicate packages from final package list

[viveksahu26]

closes: #101

This PR resolves the duplicate packages from final package list. It identifies the duplicacy of package by following:

PURL match: If the PURL matches, it's a duplicate; no need to check further.
CPE match: If the CPE matches, it's a duplicate; no need to check further.
Name-Version match: If the Name and Version match, it's a duplicate; no need to check further.
Checksum match: If the Checksum matches, it's a duplicate; no need to check further.

Reference: #101 (comment)

TODO: To test against some more SBOMs.