Fortress: disable Ubuntu Focal CI (#168)

Removed Bionic and Focal CI jobs from workflow.

Signed-off-by: Steve Peters <scpeters@openrobotics.org>

Author: scpeters

.github/workflows/ci.yml

@@ -9,24 +9,6 @@ on:
       - 'main'
 
 jobs:
-  bionic-ci:
-    runs-on: ubuntu-latest
-    name: Ubuntu Bionic CI
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-      - name: Compile and test
-        id: ci
-        uses: ignition-tooling/action-ignition-ci@bionic
-  focal-ci:
-    runs-on: ubuntu-latest
-    name: Ubuntu Focal CI
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-      - name: Compile and test
-        id: ci
-        uses: ignition-tooling/action-ignition-ci@focal
   jammy-ci:
     runs-on: ubuntu-latest
     name: Ubuntu Jammy CI