Filters > Colour > Color shift, and set the shift to 60°. Note that this is an SVG filter which may render differently in different browsers, or may also slow down rendering.
Or if you want to physically change the colours without using a filter, there's also Extensions > Colour > HSL Adjust. The Hue values are different from the Colour Shift filter and go from -360 to +360, so use a value of 30 instead of 60, but you may also have to tweak the lightness too.