MAINT: fix CI in prep for release (#659)

* CI: no need for pyarrow workaround any more

* TST: check if matrix combo is OS dependent or version dependent

* DEBUG: checking pillow for OS dependent issue

.github/workflows/tests.yml

@@ -28,25 +28,35 @@ jobs:
             python-version: "3.12"
             sphinx: "~=8.0"
             myst-parser: "~=4.0"
+            pillow: "==11.0.0"
           - os: macos-latest
             python-version: "3.12"
             sphinx: "~=8.0"
             myst-parser: "~=4.0"
+            pillow: "==11.0.0"
+          - os: ubuntu-latest
+            python-version: "3.12"
+            sphinx: "~=8.0"
+            myst-parser: "~=4.0"
+            pillow: "==11.0.0"
           # Oldest known-compatible dependencies
           - os: ubuntu-latest
             python-version: "3.9"
             sphinx: "==5.0.0"
             myst-parser: "==1.0.0"
+            pillow: "==11.0.0"
           # Mid-range dependencies
           - os: ubuntu-latest
             python-version: "3.11"
             sphinx: "==7.0.0"
             myst-parser: "==3.0.0"
+            pillow: "==11.0.0"
           # Newest known-compatible dependencies
           - os: ubuntu-latest
             python-version: "3.12"
             sphinx: "==8.0.2"
             myst-parser: "==4.0.0"
+            pillow: "==11.0.0"
 
     runs-on: ${{ matrix.os }}
 
@@ -61,11 +71,7 @@ jobs:
     - name: Install myst-nb with Sphinx ${{ matrix.sphinx }}
       shell: bash
       run: |
-        # Temporary: for python 3.13 we need the nightly pyarrow wheels
-        if [[ ${{ matrix.python-version }} == '3.13' ]] ; then
-          PIP_EXTRA_INDEX_URL=https://pypi.anaconda.org/scientific-python-nightly-wheels/simple pip install --pre pyarrow
-        fi
-        pip install --upgrade "Sphinx${{ matrix.sphinx }}" "myst-parser${{ matrix.myst-parser }}" -e .[testing]
+        pip install --upgrade "Sphinx${{ matrix.sphinx }}" "myst-parser${{ matrix.myst-parser }}" "pillow${{ matrix.pillow }}" -e .[testing]
         pip freeze
 
     - name: Run pytest