fix: check package should work

This is based on the pyscaffold template and seems to fix the now failing check package

.github/workflows/tox.yml

@@ -36,6 +36,9 @@ jobs:
     - name: Check code format with black
       if: matrix.python-version == '3.9'
       run: tox -e black
+    - name: Build package
+      if: matrix.python-version == '3.9'
+      run: tox -e build
     - name: Check package
       if: matrix.python-version == '3.9'
       run: tox -e check_package

tox.ini

@@ -45,11 +45,31 @@ commands =
     pylint --rcfile=setup.cfg {envsitepackagesdir}/{env:package}
     # This does not check files in 'tests/utils/application'
 
+[testenv:{build,clean}]
+description =
+    build: Build the package in isolation according to PEP517, see https://github.com/pypa/build
+    clean: Remove old distribution files and temporary build artifacts (./build and ./dist)
+# https://setuptools.pypa.io/en/stable/build_meta.html#how-to-use-it
+skip_install = True
+changedir = {toxinidir}
+deps =
+    build: build[virtualenv]
+passenv =
+    SETUPTOOLS_*
+commands =
+    clean: python -c 'import shutil; [shutil.rmtree(p, True) for p in ("build", "dist", "docs/_build")]'
+    clean: python -c 'import pathlib, shutil; [shutil.rmtree(p, True) for p in pathlib.Path("src").glob("*.egg-info")]'
+    build: python -m build {posargs}
+# By default, both `sdist` and `wheel` are built. If your sdist is too big or you don't want
+# to make it available, consider running: `tox -e build -- --wheel`
+
 [testenv:check_package]
+changedir = {toxinidir}
+skip_install = True
 deps =
     twine
 commands =
-    twine check --strict {distdir}/*
+    python -m twine check dist/*
 
 [testenv:flake8]
 deps = flake8