function setUint8( arr, idx, value ) {
	arr[ idx ] = value;
}
Sets an element in a `Uint8Array`.

@private
@param {Uint8Array} arr - input array
@param {NonNegativeInteger} idx - element index
@param {number} value - value to set

@example
var Uint8Array = require( '@stdlib/array/uint8' );

var arr = new Uint8Array( 4 );

setUint8( arr, 2, 3 );

var v = arr[ 2 ];
// returns 3