Add PYTEST_ADDOPTS: "--color=yes" to CI

ref:
pytest-dev/pytest#7443 (comment)

https://github.com/pytest-dev/pytest/blob/7378f35b035a75472330cc9ed65d90d127941309/.github/workflows/test.yml#L18-L19

.github/workflows/ci.yml

@@ -23,6 +23,7 @@ jobs:
     env:
       KEYVERSION: v1 # If you don't want to cache (intel fortran), you should change KEYVERSION.
       FC: mpiifort # MPI-Intel-Fortran
+      PYTEST_ADDOPTS: "--color=yes"
     steps:
       - uses: actions/checkout@v3
       - name: cache install