Add Pairwise to the list of projects using Semaphore

[vplasencia]

Description

Project info:

{
        "name": "Pairwise",
        "tagline": "A fun pseudonymous way to signal in Retro Funding 4.",
        "categories": ["Retro Funding", "Public Goods", "Privacy", "Community"],
        "pse": false,
        "icon": "",
        "links": {
            "github": "https://github.com/GeneralMagicio/pairwise-RPGF4",
            "website": "https://www.pairwise.vote/"
        }
    }