feat: include tests and docs in sdist archives (#1142)

feat: Include tests and docs in sdist archives

Include documentation and test files in source distributions, in order
to make them more useful for packagers (Linux distributions, Conda).
Testing is an important part of packaging process, and at least Gentoo
users have requested offline documentation for Python packages.
Furthermore, the COPYING file was missing from sdist, even though it was
referenced in README.

pyproject.toml

@@ -27,6 +27,12 @@ classifiers=[
 packages = [
     { include = "zeroconf", from = "src" },
 ]
+include = [
+    { path = "CHANGELOG.md", format = "sdist" },
+    { path = "COPYING", format = "sdist" },
+    { path = "docs", format = "sdist" },
+    { path = "tests", format = "sdist" },
+]
 
 [tool.poetry.urls]
 "Bug Tracker" = "https://github.com/python-zeroconf/python-zeroconf/issues"