Remove inbound request signature verification (closes #279)

internal/server/routes.go

@@ -237,10 +237,6 @@ func (s *Server) setupSourceRoutes() {
 			"/entrypoints/{entrypointID}/toggle",
 			s.h.HandleEntrypointToggle(),
 		)
-		r.Post(
-			"/entrypoints/{entrypointID}/secret",
-			s.h.HandleEntrypointSecret(),
-		)
 		r.Post("/targets", s.h.HandleTargetCreate())
 		// The edit form is the one page that renders a target's
 		// destination URL and header values in full; see