Add tests directory to source distribution (#285)

Author: yohaann196

pyproject.toml

@@ -41,7 +41,7 @@ build-backend = "uv_build"
 [tool.uv.build-backend]
 module-name = "dj_database_url"
 module-root = ""
-source-include = ["dj_database_url/py.typed"]
+source-include = ["dj_database_url/py.typed", "tests"]
 
 [tool.black]
 skip-string-normalization = 1