tox fixes

This commit was sponsored by Devin Prater, rockstar, Derek Veit, and
my other patrons.  If you want to join them, you can support my work
at https://glyph.im/patrons/.

docs/conf.py

@@ -42,7 +42,7 @@
 import pathlib
 import subprocess
 _project_root = pathlib.Path(__file__).parent.parent
-_source_root = _project_root
+_source_root = _project_root / "src"
 
 _git_reference = subprocess.run(
     ["git", "rev-parse", "--abbrev-ref", "HEAD"],

tox.ini

@@ -1,6 +1,7 @@
 [tox]
 envlist = lint,{pypy3,py38,py310,py311}-mypy,coverage-clean,{pypy3,py38,py310,py311}-{extras,noextras},coverage-report,docs
 
+isolated_build = true
 
 [testenv]
 deps =
@@ -15,8 +16,8 @@ deps =
     pytest
 
 commands =
-    {extras,noextras}: coverage run --parallel --source automat -m pytest -s -rfEsx automat/_test
-    mypy: mypy {posargs:automat}
+    {extras,noextras}: coverage run --parallel --source src -m pytest -s -rfEsx src/automat/_test
+    mypy: mypy {posargs:src/automat}
 
 depends =
     coverage-clean
@@ -43,7 +44,7 @@ commands = pytest --benchmark-only benchmark/
 
 [testenv:lint]
 deps = black
-commands = black --check automat
+commands = black --check src
 
 [testenv:pypy3-benchmark]
 deps = {[testenv:benchmark]deps}