Add input bindings for bone indices and weights

vert.glsl

@@ -2,6 +2,8 @@
 
 layout(location = 0) in vec3 position;
 layout(location = 1) in vec3 normal;
+layout(location = 2) in uvec4 bone_indices;
+layout(location = 3) in vec4 weights;
 
 layout(location = 0) out vec3 frag_normal;