Clarify CI check environment (#112)

By adding an empty tag we don't need to show a fake docker on the platforms that are natively checked (windows/macos).

.github/workflows/build-crate.yml

@@ -8,7 +8,7 @@ on:
 jobs:
 
   build:
-    name: HOST:${{ matrix.os }} DOCK:${{ matrix.tag }}
+    name: ${{ matrix.os }}::${{ matrix.tag }}
 
     runs-on: ${{ matrix.os }}
 
@@ -19,23 +19,30 @@ jobs:
           - ubuntu-latest
           - windows-latest
         tag:
-          - centos-latest-community-2019
+          - centos-latest-community-latest
           - community-current          
           - debian-stable          
           - ubuntu-lts
+          - ""
         exclude: # inclusions don't allow to add arrays of values to a scenario
+          - os: ubuntu-latest
+            tag: ""
           - os: macos-latest
             tag: centos-latest-community-2019
           - os: macos-latest
             tag: community-current
           - os: macos-latest
             tag: debian-stable
+          - os: macos-latest
+            tag: ubuntu-lts
           - os: windows-latest
             tag: centos-latest-community-2019
           - os: windows-latest
             tag: community-current
           - os: windows-latest
             tag: debian-stable
+          - os: windows-latest
+            tag: ubuntu-lts
 
     steps:
     - name: Check out alire-index