CI-unixish-docker.yml: added alpine:3.23

Author: firewave

.github/workflows/CI-unixish-docker.yml

@@ -20,7 +20,7 @@ jobs:
 
     strategy:
       matrix:
-        image: ["ubuntu:24.04", "ubuntu:25.10"]
+        image: ["ubuntu:24.04", "ubuntu:25.10", "alpine:3.23"]
       fail-fast: false # Prefer quick result
 
     runs-on: ubuntu-22.04
@@ -45,6 +45,7 @@ jobs:
           apt-get install -y cmake g++ make libxml2-utils libpcre3-dev
 
       - name: Install missing software (gui) on latest ubuntu
+        if: contains(matrix.image, 'ubuntu')
         run: |
           apt-get install -y qt6-base-dev qt6-charts-dev qt6-tools-dev