It's not an pro-discrimination bill. It's an anti-discrimination bill.
In fact, it's really not much more than a restatement of section 4 of the Texas Bill of Rights, explicitly extending this basic protection to employees, contractors, and anyone else conducting official business with the state.
No religious test shall ever be required as a qualification to any office, or public trust, in this State; nor shall any one be excluded from holding office on account of his religious sentiments, provided he acknowledge the existence of a Supreme Being.
From The Statesmen: House gives preliminary OK to ‘Save Chick-fil-A’ bill
From openstates: SB 1978 - Texas Senate (86)