Fix docstyle check

Author: BloodAxe

.appveyor.yml

@@ -14,7 +14,7 @@ environment:
 install:
   - '%PYTHON%\python.exe -m pip install -U pip wheel setuptools'
   - '%PYTHON%\python.exe -m pip install .[tests]'
-  - '%PYTHON%\python.exe -m pip install flake8 flake8-docstrings'
+  - '%PYTHON%\python.exe -m pip install "pydocstyle<4.0.0" flake8 flake8-docstrings'
 
 test_script:
   - '%PYTHON%\python.exe -m pytest'

.travis.yml

@@ -18,7 +18,7 @@ matrix:
 install:
 - if [[ "$TEST_MODE" == "DOCS" ]]; then pip install -q .; fi
 - if [[ "$TEST_MODE" != "DOCS" ]]; then pip install -q .[tests]; fi
-- if [[ "$TEST_MODE" != "DOCS" ]]; then pip install flake8 flake8-docstrings; fi
+- if [[ "$TEST_MODE" != "DOCS" ]]; then pip install "pydocstyle<4.0.0" flake8 flake8-docstrings; fi
 script:
 - if [[ "$TEST_MODE" != "DOCS" ]]; then pytest; fi
 - if [[ "$TEST_MODE" != "DOCS" ]]; then flake8; fi