update mybinder link for 0.12.1
update mybinder link for 0.12.1

jpallas/beakerx,twosigma/beaker-notebook,jpallas/beakerx,twosigma/beakerx,twosigma/beaker-notebook,jpallas/beakerx,twosigma/beakerx,twosigma/beakerx,jpallas/beakerx,twosigma/beaker-notebook,twosigma/beaker-notebook,twosigma/beakerx,twosigma/beaker-notebook,jpallas/beakerx,twosigma/beakerx,jpallas/beakerx,twosigma/beakerx