SOFTWARE-5924: Remove OSG 3.6 from github workflows build matrix

Author: mwestphall

.github/workflows/build-container.yml

@@ -32,7 +32,7 @@ jobs:
           - image: 'nvidia/cuda:11.8.0-runtime-rockylinux8'
             tag_str: 'cuda_11_8_0'
         repo: ['development', 'testing', 'release']
-        series: ['3.6', '23']
+        series: ['23']
     needs: make-date-tag
     steps:
     - name: checkout docker-software-base