Use a dev extra instead of installing with --pre

pyproject.toml

@@ -25,8 +25,8 @@ classifiers = [
   "Topic :: Utilities",
 ]
 dependencies = [
-    "dissect.cstruct>3,<5",
-    "dissect.util>2,<4",
+    "dissect.cstruct>=4.dev,<5",
+    "dissect.util>=3,<4",
 ]
 dynamic = ["version"]
 
@@ -35,6 +35,12 @@ homepage = "https://dissect.tools"
 documentation = "https://docs.dissect.tools/en/latest/projects/dissect.ntfs"
 repository = "https://github.com/fox-it/dissect.ntfs"
 
+[project.optional-dependencies]
+dev = [
+    "dissect.cstruct>=4.0.dev,<5.0.dev",
+    "dissect.util>=3.0.dev,<4.0.dev",
+]
+
 [tool.black]
 line-length = 120
 

tox.ini

@@ -11,17 +11,11 @@ minversion = 4.4.3
 requires = virtualenv>=20.16.6
 
 [testenv]
+extras = dev
 deps =
     pytest
     pytest-cov
     coverage
-# Unfortunately, tox does not allow separate installation flags for the project
-# dependencies and the test dependencies. When running tox, we want to install the
-# project dependencies with the --pre flag, so that we get the latest version of all
-# dependencies. We do the installation step ourselves for this reason.
-skip_install = true
-commands_pre =
-    pip install --pre -e .
 commands =
     pytest --basetemp="{envtmpdir}" {posargs:--color=yes --cov=dissect --cov-report=term-missing -v tests}
     coverage report