DOC: fixed using IP.prompt_manager which is removed from IPython 5.x (#14004)

* fixed using IP.prompt_manager which is removed from IPython 5.x

class promptManager has removed in IPython 5.x, but this file
still using that class, so it makes AttributeError.

Author: znmean

doc/sphinxext/ipython_sphinxext/ipython_directive.py

@@ -802,10 +802,14 @@ def setup(self):
         # reset the execution count if we haven't processed this doc
         #NOTE: this may be borked if there are multiple seen_doc tmp files
         #check time stamp?
-        if not self.state.document.current_source in self.seen_docs:
+        if self.state.document.current_source not in self.seen_docs:
             self.shell.IP.history_manager.reset()
             self.shell.IP.execution_count = 1
-            self.shell.IP.prompt_manager.width = 0
+            try:
+                self.shell.IP.prompt_manager.width = 0
+            except AttributeError:
+                # GH14003: class promptManager has removed after IPython 5.x
+                pass
             self.seen_docs.add(self.state.document.current_source)
 
         # and attach to shell so we don't have to pass them around