Are carbonated drinks considered dangerous goods for air freight?
Each operator is of course entitled to apply stricter regulations, but there's no restriction against carbonated drinks in the IATA-DGR (based on the ICAO TI, which sets out the framework for dangerous goods regulations).

The maximum amount of pure CO2 an operator may transport in approved packaging (iaw. IATA-DGR) is:


In gaseous form (UN1013): 150 kg on cargo only aircraft, and 75 kg in passenger/cargo aircraft.
In liquid form (UN2187): 500 kg on cargo only aircraft, and 50 kg in passenger/cargo aircraft.
In solid form "dry ice" (UN1845): 200 kg for both cargo and passenger/cargo aircraft