iShares USD Treasury Bond 1-3yr UCITS ETF CHF Hedged (Acc) would be the best fit, as far as I can tell. However, while the bond duration is fairly short, it’s still too long term for your goal, in my opinion. I don’t see any shorter term CHF-hedged gov bond ETF, though.
I would simply move the money to a flexible savings account (Yuh is completely flexible but you only get 1% p.a.).
Related topic: Short guide to CHF fixed income options