adds py39 pyproject.toml (pytorch#2380)

bibhabasumohapatra · vfdev-5 · Ishan-Kumar2 · commit 5ef7de759da3 · 2021-12-27T01:20:34.000+05:30
Co-authored-by: vfdev &lt;vfdev.5@gmail.com&gt;
diff --git a/pyproject.toml b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.black]
 line-length = 120
-target-version = ['py37', 'py38']
+target-version = ['py37', 'py38', 'py39']
 include = '\.pyi?$'
 exclude = '''
 
