David Robb Labor EditorClaiming that “systemic racism” is to blame for a lack of “economic parity,” more than three dozen live television musicians have signed an open letter to the TV networks calling for parity with their colleagues – actors, writers and directors – in the area of wages, health care contributions and residuals payments on streaming platforms.Signers include John Baptiste, the bandleader for The Late Show with Stephen Colbert; Eli Brueggemann, music director for Saturday Night