Support older pytest versions

xdist/dsession.py

@@ -521,7 +521,7 @@ class DSession:
         # prohibit collection of test items in master process
         return True
 
-    @pytest.hookimpl(trylast=True)
+    @pytest.mark.trylast
     def pytest_xdist_make_scheduler(self, numnodes, log, config):
         dist = config.getvalue("dist")
         if dist == "load":

xdist/newhooks.py

@@ -47,7 +47,7 @@ def pytest_xdist_node_collection_finished(node, ids):
     """
 
 
-@pytest.hookspec(firstresult=True)
+@pytest.mark.firstresult
 def pytest_xdist_make_scheduler(numnodes, log, config):
     """Return a node scheduler implementation, or None.
     """