Employ a matrix strategy for the version of the CLI being setup

Author: swinton

.github/workflows/test.yml

@@ -1,6 +1,6 @@
 name: Test
 
-on: [ push ]
+on: [ push, pull_request ]
 
 jobs:
   test:
@@ -9,13 +9,14 @@ jobs:
     strategy:
       matrix:
         os: [macos-latest, windows-latest, windows-2016, ubuntu-18.04]
+        version: [1.1.0, 1.0.0]
     steps:
     - name: Checkout
       uses: actions/checkout@v2
 
     - name: Setup gh
       uses: ./
       with:
-        version: 1.1.0
+        version: ${{ matrix.version }}
 
     - run: gh --version