include tests in pypi package

This commit adds the tests directory when packaging up for pypi. This is in response to a request from @pacoesteban (GitHub user) who is the maintainer for the OpenBSD port of ephemetoot.

README.md

@@ -44,6 +44,8 @@ You can use `ephemetoot` to delete [Mastodon](https://github.com/tootsuite/masto
 * they are individually listed to be kept
 
 ## Contributing
+ephemetoot is packaged using `poetry` and tested using `pytest`.
+
 For all bugs, suggestions, pull requests or other contributions, please check the [contributing guide](./docs/contributing.md).
 
 ## License

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "ephemetoot"
-version = "3.1.0"
+version = "3.1.1-alpha.1"
 description = "A command line tool to delete your old toots"
 authors = ["Hugh Rundle <ephemetoot@hugh.run>"]
 license = "GPL-3.0-or-later"
@@ -15,6 +15,7 @@ classifiers = [
 ]
 include = [
     "LICENSE",
+    "tests"
 ]
 
 [tool.poetry.dependencies]