Update test.yml

Author: sinoru

.github/workflows/test.yml

@@ -13,8 +13,13 @@ jobs:
     runs-on: ${{ matrix.operating-system }}
     strategy:
       matrix:
-        operating-system: ["ubuntu-18.04", "ubuntu-20.04", "macos-10.15"]
-        swift-version: ["5.3"]
+        operating-system: ["ubuntu-16.04", "ubuntu-18.04", "ubuntu-20.04", "macos-10.15"]
+        swift-version: ["5.0.3", "5.1.5", "5.2.5", "5.3.3"]
+        exclude:
+          - operating-system: "ubuntu-20.04"
+            swift-version: "5.0.3"
+          - operating-system: "ubuntu-20.04"
+            swift-version: "5.1.5"
     steps:
       - name: Checkout
         uses: actions/checkout@v2