remove ostree ISO test from github workflow

Author: oliverkurth

.github/workflows/poi-vcf.yml

@@ -251,7 +251,7 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                name: [minimal, ostree]
+                name: [minimal]
         steps:
             - name: Checkout code
               uses: actions/checkout@master