Fix post-install.sh venv creation

Author: OCopping

.devcontainer/post-install.sh

@@ -1,5 +1,5 @@
 pip install --upgrade pip
 pdm python install
-pdm venv create --force
-pdm use -f .venv
+pdm venv create --force --name guibuilder
+pdm use --venv guibuilder
 pdm install -G dev