Enable reporting of encoding warnings. (#578)

* Enable reporting of encoding warnings.

* Add changelog

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Adi Roiban <adiroiban@gmail.com>

noxfile.py

@@ -20,6 +20,7 @@ def pre_commit(session: nox.Session) -> None:
 # Keep list in-sync with ci.yml/test-linux & pyproject.toml
 @nox.session(python=["pypy3.8", "3.8", "3.9", "3.10", "3.11", "3.12"])
 def tests(session: nox.Session) -> None:
+    session.env["PYTHONWARNDEFAULTENCODING"] = "1"
     session.install("Twisted", "coverage[toml]")
     posargs = list(session.posargs)
 

src/towncrier/newsfragments/561.misc.rst

@@ -0,0 +1 @@
+Enable reporting of EncodingWarnings when running tests.