Update the SM1 gains

the quoted SM1 gains aren't quite right, we (i.e. arnaud.lefur) think that better values are:

gains = dict(b=np.array([1.32, 1.31, 1.34, 1.26, 1.36, 1.31, 1.34, 1.26]),
             r=np.array([1.181009, 1.169722, 1.174006, 1.196543, 1.250177, 1.259089, 1.247757, 1.207198]),
             rold=np.array([1.24, 1.24, 1.27, 1.18, 1.26, 1.20, 1.24, 1.26]),
            )

where "rold" are the current values that we're using for both the r and b arms.

Please update obs_pfs. In the longer term (Gen3) this will be in a pure-data product, but for now please just use the old mechanism.