[DOCS] Fix vta tutorial (#4809)

tests/scripts/task_python_docs.sh

@@ -25,6 +25,7 @@ rm -rf docs/_build/html/javadoc
 
 # remove stale tutorials and always build from scratch.
 rm -rf docs/tutorials
+rm -rf docs/vta/tutorials
 
 # C++ doc
 make doc

vta/tutorials/autotvm/tune_relay_vta.py

@@ -348,7 +348,8 @@ def tune_and_evaluate(tuning_opt):
     # Perform task extraction on Relay program
     print("Extract tasks...")
     relay_prog, params = compile_network(env, target, network, start_pack, stop_pack)
-    tasks = autotvm.task.extract_from_program(func=relay_prog,
+    mod = relay.Module.from_expr(relay_prog)
+    tasks = autotvm.task.extract_from_program(mod,
                                               params=params,
                                               ops=(tvm.relay.op.nn.conv2d,),
                                               target=target,