chore: deprecate Ubuntu 18.04 as not used by any LinuxGSM images

a

Author: dgibbs64

.github/workflows/docker-publish.yml

@@ -94,49 +94,9 @@ jobs:
             gameservermanagers/linuxgsm:ubuntu-20.04
             ghcr.io/gameservermanagers/linuxgsm:ubuntu-20.04
 
-  build-ubuntu-1804:
-    name: Build Ubuntu 18.04
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Setup QEMU
-        uses: docker/setup-qemu-action@v3
-
-      - name: Setup Docker Buildx
-        uses: docker/[email protected]
-
-      - name: Build
-        run: docker build -t gameservermanagers/linuxgsm:ubuntu-18.04 -f ./Dockerfile.ubuntu-1804 .
-
-      - name: Login to DockerHub
-        uses: docker/[email protected]
-        with:
-          username: ${{ secrets.DOCKER_HUB_USERNAME }}
-          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
-
-      - name: Login to GitHub Container Registry
-        uses: docker/[email protected]
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: Build and push (Ubuntu 18.04)
-        uses: docker/[email protected]
-        with:
-          context: .
-          file: ./Dockerfile.ubuntu-1804
-          platforms: linux/amd64
-          push: true
-          tags: |
-            gameservermanagers/linuxgsm:ubuntu-18.04
-            ghcr.io/gameservermanagers/linuxgsm:ubuntu-18.04
-
   package-cleanup:
     name: Cleanup Old GitHub Packages
-    needs: [ build-ubuntu-1804, build-ubuntu-2004, build-ubuntu-2204 ]
+    needs: [ build-ubuntu-2004, build-ubuntu-2204 ]
     runs-on: ubuntu-latest
     steps:
       - name: Delete Package Versions

Dockerfile.ubuntu-1804

@@ -21,4 +21,3 @@ LinuxGSM is a command-line tool for quick, simple deployment and management of L
 - `latest`, `ubuntu` - Latest Ubuntu LTS release
 - `ubuntu-22.04` - Ubuntu 22.04 LTS 'Jammy Jackalope'
 - `ubuntu-20.04` - Ubuntu 20.04 LTS 'Focal Fossa'
-- `ubuntu-18.04` - Ubuntu 18.04 LTS 'Bionic Beaver'