The salary of no state officer or employee payable by the Commonwealth and not specifically fixed by law shall be increased, or authorized to be increased, without the written consent of the Governor. The salary of no officer or employee of any state institution, board, commission or agency payable by the Commonwealth and not specifically fixed by law, shall be increased, or authorized to be increased, without prior written authorization of such board or commission and the written consent of the Governor. Any violation of this section shall constitute misfeasance in office. Nothing herein shall apply to teachers in the elementary or secondary schools of the Commonwealth or to employees receiving compensation not in excess of $100 per month.