Install primer.json (used by black-primer by default) with black (#2154)

Fixes https://github.com/psf/black/issues/2153

CHANGES.md

@@ -1,5 +1,11 @@
 ## Change Log
 
+### Unreleased
+
+#### _Packaging_
+
+- Install `primer.json` (used by `black-primer` by default) with black. (#2154)
+
 ### 21.4b1
 
 #### _Black_

setup.py

@@ -64,7 +64,11 @@ def get_long_description() -> str:
     ext_modules=ext_modules,
     packages=["blackd", "black", "blib2to3", "blib2to3.pgen2", "black_primer"],
     package_dir={"": "src"},
-    package_data={"blib2to3": ["*.txt"], "black": ["py.typed"]},
+    package_data={
+        "blib2to3": ["*.txt"],
+        "black": ["py.typed"],
+        "black_primer": ["primer.json"],
+    },
     python_requires=">=3.6.2",
     zip_safe=False,
     install_requires=[