Oscar winners Renée Zellweger and Sissy Spacek will star with rising talent Mia Threapleton in “A Woman in the Sun.” Black Bear and Artist Equity have partnered with Zellweger’s Big Picture Co. on the drama, which marks the directorial debut of “Nyad” writer Julia Cox. Black Bear will introduce the project to international buyers at Cannes. Zellweger is producing the project alongside Carmella Casinelli (for Big Picture Co.) and Kim Roth, with Greg Gertmenian co-producing. Production is slated