remove install requirements on CI

Author: dakk

.github/workflows/ci.yaml

@@ -27,7 +27,6 @@ jobs:
         sudo apt-get install libgtk-4-dev libgtk-4-1
         pip install git+https://github.com/vext-python/vext@32ad4d1c5f45797e244df1d2816f76b60f28e20e
         pip install tox
-        pip install -r requirements.txt
 
     - name: Run tests
       run: pip install .