Merge pull request #1131 from mariocj89/master

ci: Remove the need of upgrading pip/setuptools

.github/workflows/validate.yml

@@ -32,8 +32,6 @@ jobs:
         uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python-version }}
-      - name: Update pip and setuptools
-        run: python -m pip install -U pip setuptools
       - name: Install dependencies
         run: python -m pip install -U tox
       - name: Install zic (Windows)

tox.ini

@@ -11,6 +11,12 @@ envlist = py27,
           docs
 minversion = 2.9.0
 skip_missing_interpreters = true
+isolated_build = true
+
+[testenv:.package]
+# no additional dependencies besides PEP 517 for building the package
+# Needed as we are running with an old version of tox.
+deps =
 
 [testenv]
 description = run the unit tests with pytest under {basepython}