fix .github/workflows, no need for a docker proxy

.github/workflows/photon-os-installer.yml

@@ -1,8 +1,6 @@
 name: photon-os-installer CI
 
-on:
-  pull_request:
-    branches: [master]
+on: [pull_request, push, workflow_dispatch]
 
 jobs:
   build:
@@ -16,7 +14,7 @@ jobs:
       run: |
         POI_IMAGE_NAME=photon/installer:${{ github.sha }}
         cd docker
-        docker build -t $POI_IMAGE_NAME --build-arg DOCKER_PROXY=dockerhub.artifactory.eng.vmware.com/ --build-context poi-helper=$(realpath $(pwd)/..) .
+        docker build -t $POI_IMAGE_NAME --build-context poi-helper=$(realpath $(pwd)/..) .
         docker system prune -f
 
   test:
@@ -37,6 +35,9 @@ jobs:
         python -m pip install --upgrade pip
         pip install -r requirements.txt  # Ensure this file lists the necessary dependencies
 
+    - name: install pytest
+      run: pip install pytest
+
     - name: Run Pytest
       run: |
         pytest -x tests/poi-container-test.py