[pox-5] Set POX_5_SBTC_DEPOSIT_MAX_FEE_SATS

[aaronb-stacks]

We need to set POX_5_SBTC_DEPOSIT_MAX_FEE_SATS.

This is currently set to 80_000 sats, but we may want to go even higher just for future proofing?

[djordon-stacks]

I don't think that we should increase that value at all. If anything, we may want to lower it. But I'd advise against that as well, so we have a bit of flexibility as we roll this out. Instead, we'll try outside-of-stacks-core ways of keeping fees low. So, I don't think that there is anything to do here, and we could close this issue.