ci: Use PY_COLORS to force colored output

This should also color tox output, and it doesn't conflict with PYTEST_ADDOPTS
being used for coverage options.

.github/workflows/ci.yml

@@ -1,5 +1,7 @@
 name: CI
 on: [push, pull_request]
+env:
+  PY_COLORS: "1"
 
 jobs:
   linters:
@@ -161,8 +163,6 @@ jobs:
             python -m pip install -U pip
             python -m pip install -U -r misc/requirements/requirements-tox.txt
       - name: "Run ${{ matrix.testenv }}"
-        env:
-          PYTEST_ADDOPTS: "--color=yes"
         run: "tox -e ${{ matrix.testenv}} -- ${{ matrix.args }}"
       - name: Analyze backtraces
         run: "bash scripts/dev/ci/backtrace.sh ${{ matrix.testenv }}"

tox.ini

@@ -14,7 +14,7 @@ setenv =
     pyqt{,57,59,510,511,512,513,514,515}: LINK_PYQT_SKIP=true
     pyqt{,57,59,510,511,512,513,514,515}: QUTE_BDD_WEBENGINE=true
     cov: PYTEST_ADDOPTS=--cov --cov-report xml --cov-report=html --cov-report=
-passenv = PYTHON DISPLAY XAUTHORITY HOME USERNAME USER CI XDG_* QUTE_* DOCKER QT_QUICK_BACKEND PYTEST_ADDOPTS
+passenv = PYTHON DISPLAY XAUTHORITY HOME USERNAME USER CI XDG_* QUTE_* DOCKER QT_QUICK_BACKEND PY_COLORS
 basepython =
     py3: {env:PYTHON:python3}
     py35: {env:PYTHON:python3.5}