Minor fixes - reduce lines (#1293)

* Update opengl_renderer.py

* Update point_cloud_mobject.py

Author: donno2048

manim/mobject/types/point_cloud_mobject.py

@@ -72,17 +72,6 @@ def set_color_by_gradient(self, *colors):
         )
         return self
 
-        start_rgba, end_rgba = list(map(color_to_rgba, [start_color, end_color]))
-        for mob in self.family_members_with_points():
-            num_points = mob.get_num_points()
-            mob.rgbas = np.array(
-                [
-                    interpolate(start_rgba, end_rgba, alpha)
-                    for alpha in np.arange(num_points) / float(num_points)
-                ]
-            )
-        return self
-
     def set_colors_by_radial_gradient(
         self, center=None, radius=1, inner_color=WHITE, outer_color=BLACK
     ):

manim/renderer/opengl_renderer.py

@@ -274,7 +274,6 @@ def render_mobjects(self, mobs):
 
     def render_render_group(self, render_group):
         shader_wrapper = render_group["shader_wrapper"]
-        shader_program = render_group["prog"]
         self.set_shader_uniforms(render_group["prog"], render_group["shader_wrapper"])
         self.update_depth_test(self.context, shader_wrapper)
         render_group["vao"].render(int(shader_wrapper.render_primitive))