Use ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION for CentOS 7 builds

- see actions/runner#2906

.github/workflows/build.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches: 
       - master
+      - disable-oldschool
   pull_request:
 
 concurrency:
@@ -115,6 +116,8 @@ jobs:
             container_os_python_package: 'python3-devel'
             configuration: 'release'
     runs-on: ubuntu-latest
+    env:
+      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: 'true'
     container: '${{ matrix.container_os }}:${{ matrix.container_os_version }}'
     steps:
     - name: Change centos archive repository