`async` is a reserved keyword in Python 3.7

[benmaier (Benjamin F. Maier)]

The keyword async in graph_tool.draw.interactive_window in line 1185 is reserved in Python 3.7, so it has been changed to sync in the active repository (see ​https://git.skewed.de/count0/graph-tool/blob/master/src/graph_tool/draw/gtk_draw.py#1185 ), however in the port it's still called async, raising the following error:

In [1]: import graph_tool.all as gt
dbus[65811]: Dynamic session lookup supported but failed: launchd did not provide a socket path, verify that org.freedesktop.dbus-session.plist is loaded!
Traceback (most recent call last):

  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/IPython/core/interactiveshell.py", line 2961, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)

  File "<ipython-input-1-f96fce82bbfd>", line 1, in <module>
    import graph_tool.all as gt

  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/graph_tool/all.py", line 35, in <module>
    from graph_tool.draw import *

  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/graph_tool/draw/__init__.py", line 875, in <module>
    from .cairo_draw import graph_draw, cairo_draw, get_hierarchy_control_points, default_cm

  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/graph_tool/draw/cairo_draw.py", line 1491, in <module>
    from .gtk_draw import *

  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/graph_tool/draw/gtk_draw.py", line 1185
    update_layout=True, async=False, no_main=False, **kwargs):
                            ^
SyntaxError: invalid syntax

[mamoll (Mark Moll)]

In 3b313aa8727631273aa25dba0d359643b25ddfb0/macports-ports (master):

py-graph-tool: add upstream fix for using async keyword. Closes #57762