fix(runner): bring concurrency back

lua/lazy/manage/runner.lua

@@ -96,6 +96,7 @@ function Runner:_start()
         waiting = waiting + 1
         wait_step = s.step
       elseif not running then
+        if not self._opts.concurrency or active < self._opts.concurrency then
           local plugin = self:plugin(name)
           if s.step == #self._pipeline then
             s.task = nil
@@ -111,6 +112,7 @@ function Runner:_start()
               plugin._.working = not not s.task
             end
           end
+        end
       else
         active = active + 1
       end