Ramping A on mUSD

This proposal regards general maintenance of the mUSD contract - specifically increasing the value of the A value which makes the curve "flatter", thus producing lower slippage swaps. sUSD generally trends from $1.01 to $1.03, and so to avoid having max weights hit, we should support >+3.5% slippage.

Proposed A: 250 Supporting +3.8% and -2.3% in price diff at extreme weights

Weights: 5.100%, 32.900%, 31.000%, 31.000%
0 -> 1 price: 0.961926
0 -> 2 price: 0.962354

Weights: 12.000%, 12.000%, 12.000%, 64.000%
0 -> 3 price: 0.977043

Ramp A up over the next 7 days?