Update GitHub Actions

.github/workflows/swift-macos.yml

@@ -1,19 +1,16 @@
-name: Swift
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  build:
-
-    runs-on: macos-latest
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Build
-      run: swift build -v
-    - name: Run tests
-      run: swift test -v
+name: Swift ${{ matrix.swift }} on ${{ matrix.os }}
+runs-on: ${{ matrix.os }}
+strategy:
+  matrix:
+    os: [ubuntu-latest, macos-latest]
+    swift: ["5.4", "5.2.4"]
+steps:
+- uses: fwal/setup-swift@v1
+  with:
+    swift-version: ${{ matrix.swift }}
+- name: Get swift version
+  run: swift --version
+- name: Build
+  run: swift build -v
+- name: Test
+  run: swift test -v