Reduce maximum trade size for unsigned payment accounts to 0.003 BTC

[MwithM]

It is currently possible to trade >900 USD without signing with risky payment accounts in active markets. When the current limit of 0.01 was set, BTC price was around 40.000 USD so max amount an unsigned account could buy was 400USD and min amount to get signed was 100USD.
I propose to reduce the min-maximum amount that unsigned accounts can buy to 0.00075 BTC and 0.003 BTC. At today's 94.000 USD/BTC price, that would be approximately 70 and 280 USD.

Since account signing and trading limits have been an effective method against fraud, this is the most critical of the three proposals (#467, #469) I have made to adjust Bisq trading limits to BTC price increase, but unlike the other two I have concerns about how easy it is to implement on a technical level. In the previous change discussion, a hard fork was discussed but I don't know if it was finally necessary, as there were doubts about how to implement this critical change with a workaround.
I can't comment on that, but since it was somehow implemented, hopefully it's easier this time.