Trying to get GCC7 working on Ubuntu 20

.github/actions/setup_gcc_ubuntu/action.yml

@@ -70,6 +70,9 @@ runs:
     - name: Install gcc
       shell: bash
       run: |
+        if [[ ${{ inputs.gcc-version == 'gcc-7' }} ]]; then
+          echo "deb http://archive.ubuntu.com/ubuntu focal main universe" >> "/etc/apt/sources.list"
+        fi
         apt-get -y install ${{ inputs.gcc-version }}
         apt-get -y install g++-$( echo ${{ inputs.gcc-version }} | cut -d '-' -f 2)
         apt update && apt upgrade -y

.github/workflows/LINUX_BUILD_TEST.yml

@@ -33,9 +33,7 @@ jobs:
         # Removes unecessary jobs as jobs are generated in the order seen in the matrix.
         # "Exclude" is to keep job ordering nice i.e. keeping ubuntu jobs next to each other in the list.
         #######################################
-        exclude:      
-          - OS: 'ubuntu:20.04'
-            COMPILER: 'gcc-7'
+        exclude:
 
           # need redhat 8 for gcc 7 and 8 | redhat 9 for gcc 9 and 10
           - OS: 'redhat/ubi8:latest'