It’s been almost four years since Kelly Clarkson filed for divorce from Brandon Blackstock — and the exes are still duking it out in court. While the “Stronger” singer submitted a petition to legally end her marriage in June 2020, the former flames’ split wasn’t finalized until March 2022. Now, Clarkson and Blackstock are still fighting over a labor dispute. “While Kelly has moved on emotionally from Brandon, she has no problem being tied up with him in court if it concerns her business and career,” a source recently spilled to a news publication of The Kelly Clarkson Show host — who shares he…