Four experienced writers and editors have given their notice at the Post-Dispatch in just a few weeks' time.Stephen Deere, who covers the St. Louis County beat for the daily, has accepted a job as the City Hall reporter for the Atlanta Journal-Constitution, while Blues writer Jeremy Rutherford is heading to an online publication. Matt Franck, the paper's well-respected deputy metro editor, and longstanding TV critic Gail Pennington have also given notice.…