First, that's clearly not what happened; here's the transcript of the whole call, not a "4 minute clip":

https://www.washingtonpost.com/politics/trump-raffensperger-...

Second, as you've now been informed (and could have verified with a simple Google search), the call was not privileged, nor was it "confidential" in the sense we ordinarily mean. Disclosing it was perfectly lawful.