try to fix cirrus build by using system pip

Author: electronstudio

.cirrus.yml

@@ -47,7 +47,6 @@ pi_task:
     - cp -r raylib-c/src/external/glfw/include/GLFW /usr/local/include/
     - cp physac/src/physac.h /usr/local/include/
     - cp raygui/src/raygui.h /usr/local/include/
-    - python -m pip install --break-system-packages --upgrade pip
     - python -m pip install --break-system-packages cffi
     - python -m pip install --break-system-packages setuptools
     - python -m pip install --break-system-packages wheel