Add "autobahn" to "package_imports"

This fixes PyInstaller-generated "frozen" binaries which, without
this, fail to run with "allmydata.PackagingError: no version info
for autobahn"

fixes🎫3229

src/allmydata/_auto_deps.py

@@ -139,6 +139,7 @@ package_imports = [
     ('setuptools',       'setuptools'),
     ('eliot',            'eliot'),
     ('attrs',            'attr'),
+    ('autobahn',         'autobahn'),
 ]
 
 # Dependencies for which we don't know how to get a version number at run-time.