[AtmoNouvelleAquitaineBridge] Add new bridge for air quality in Bordeaux

[floviolleau]

Adds a bridge for Atmo Nouvelle Aquitaine air quality.

[teromene]

You have quite an inconstancy between single quotes and double quotes. We prefer using double.
Apart from that, the bridge looks good !

[teromene]

Thanks for the PR !

[dvikan]

@floviolleau

rssbridge2.ERROR Exception in RssBridge::main() {
    "type": "Error",
    "code": 0,
    "message": "Call to a member function find() on null",
    "file": "bridges/AtmoNouvelleAquitaineBridge.php",
    "line": 55,
    "url": "https://rss-bridge.org/bridge01/?action=display&bridge=AtmoNouvelleAquitaine&cities=33063&format=Mrss",
    "trace": [
        "index.php(11): RssBridge->main()",
        "lib/RssBridge.php(111): DisplayAction->execute()",
        "actions/DisplayAction.php(68): DisplayAction->createResponse()",
        "actions/DisplayAction.php(103): AtmoNouvelleAquitaineBridge->collectData()",
        "bridges/AtmoNouvelleAquitaineBridge.php(39): AtmoNouvelleAquitaineBridge->getIndexMessage()",
        "bridges/AtmoNouvelleAquitaineBridge.php(130): AtmoNouvelleAquitaineBridge->getIndex()",
        "bridges/AtmoNouvelleAquitaineBridge.php(55)"
    ]
}