remove unused inputs from instancing vertex shader

shader/instancing_vertex.glsl

@@ -1,9 +1,6 @@
 #version 330
 
 in vec3 vertexPosition;
-in vec2 vertexTexCoord;
-in vec3 vertexNormal;
-in vec4 vertexColor;
 in mat4 instanceTransform;
 
 uniform mat4 mvp;