fix CI: third try

.github/workflows/CI.yml

@@ -28,7 +28,7 @@ jobs:
       - run: pip install mkdocs-material
       - run: |
           pip install "mkdocs-material[imaging]"
-          pip install -r ./requirement.txt
+          pip install -r ./requirements.txt
           python3 -m pip install --upgrade pip
           python3 -m pip install --upgrade Pillow
       - run: mkdocs gh-deploy --force