Removing ubuntu18/gcc7 combo

.github/actions/setup_gcc_ubuntu/action.yml

@@ -59,14 +59,8 @@ runs:
     - name: Install cmake via apt
       shell: bash
       run: |
-        if [[ ${{ inputs.OS == 'ubuntu:18.04' }} ]]; then
-          NAME=bionic
-        else
-          NAME=focal
-        fi
-
         wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | tee /etc/apt/trusted.gpg.d/kitware.gpg >/dev/null && \
-        apt-add-repository "deb https://apt.kitware.com/ubuntu/ $NAME main" && \
+        apt-add-repository "deb https://apt.kitware.com/ubuntu/ focal main" && \
         apt update && apt install cmake -y
         apt upgrade -y
 

.github/workflows/LINUX_BUILD_TEST.yml

@@ -37,13 +37,6 @@ jobs:
           - OS: 'ubuntu:20.04'
             COMPILER: 'gcc-7'
 
-          - OS: 'ubuntu:18.04'
-            COMPILER: 'gcc-8'
-          - OS: 'ubuntu:18.04'
-            COMPILER: 'gcc-9'
-          - OS: 'ubuntu:18.04'
-            COMPILER: 'gcc-10'
-
           # need redhat 8 for gcc 7 and 8 | redhat 9 for gcc 9 and 10
           - OS: 'redhat/ubi8:latest'
             COMPILER: gcc-9
@@ -77,16 +70,9 @@ jobs:
 
     steps:
       #######################################
-      # Clones repo to workspace. (ubuntu 18 is missing correct glibc version
-      # for newer checkout action version i.e. use older checkout version)
-      # NOTE: may want to remove support for gcc-7 soon
+      # Clones repo to workspace
       #######################################
-      - if: ${{ contains(fromJson('["ubuntu:18.04"]'), matrix.OS) }}
-        name: checkout v3
-        uses: actions/checkout@v3
-
-      - if: ${{ !contains(fromJson('["ubuntu:18.04"]'), matrix.OS) }}
-        name: checkout v4
+      - name: checkout v4
         uses: actions/checkout@v4
 
       #######################################