issue with python3 dictionary unpacking

[andykais]

PEP 448 dictionary spreading creates invalid syntax

x = {}
merged = {**x}

becomes

x = {}
merged = {: x}

using git master version of plugin:

git+https://github.com/prettier/plugin-python.git#036c8a66c166ed710b2a0d280e4c85015a1a34c5 ("version": "0.0.0-development")