added back dash in ubuntu name

Author: FlorianReimold

.github/workflows/build-ubuntu.yml

@@ -37,9 +37,9 @@ jobs:
 
         # Get the ubuntu version
         os_version=$(lsb_release -r | awk '{print $2}')
-        echo "os_name=ubuntu${os_version}" >> "$GITHUB_ENV"
+        echo "os_name=ubuntu-${os_version}" >> "$GITHUB_ENV"
 
-        # Get cpu architecture
+        # Get cpu architecture for the package name (therefore the dpkg architecture, which differs from the arch architecture)
         echo "cpu_architecture=$(dpkg --print-architecture)" >> "$GITHUB_ENV"
         
     - name: Checkout