fix typo in value_tracker.py (#3594)

Author: yuan-xy

manim/mobject/value_tracker.py

@@ -45,7 +45,7 @@ def construct(self):
                 self.wait(1)
                 tracker -= 4
                 self.wait(0.5)
-                self.play(tracker.animate.set_value(5)),
+                self.play(tracker.animate.set_value(5))
                 self.wait(0.5)
                 self.play(tracker.animate.set_value(3))
                 self.play(tracker.animate.increment_value(-2))