Explicit non-support for tox 4

.gitignore

@@ -7,3 +7,4 @@ docs/_build/
 /htmlcov/
 /.pytest_cache/
 /.vscode/
+/.venv/

.pre-commit-config.yaml

@@ -0,0 +1,7 @@
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: check-yaml
+    -   id: end-of-file-fixer
+    -   id: trailing-whitespace

LICENSE

@@ -19,4 +19,3 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
-

docs/Makefile

@@ -17,4 +17,4 @@ help:
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile
-	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

docs/conf.py

@@ -65,7 +65,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.

docs/envlist.rst

@@ -153,4 +153,3 @@ And in your ``tox.ini``:
 
     [travis]
     unignore_outcomes = True
-

setup.py

@@ -62,13 +62,13 @@ def default_environment():
     author_email='[email protected]',
     url='https://github.com/tox-dev/tox-travis',
     license='MIT',
-    version='0.12',
+    version='0.13',
     package_dir={'': 'src'},
     packages=find_packages('src'),
     entry_points={
         'tox': ['travis = tox_travis.hooks'],
     },
-    install_requires=['tox>=2.0'],
+    install_requires=['tox>=2.0,<4'],
     python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
     classifiers=[
         'Development Status :: 4 - Beta',