Drop setup-swift (for Linux, which is the prod platform)

.github/workflows/ci.yml

@@ -26,12 +26,31 @@ env:
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
 jobs:
-  run_nightly:
+  test-validator-Linux:
+    runs-on: swift:5.8.1-focal
+    steps:
+      - name: Get swift version
+        run: swift --version
+
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Build validator
+        run: |
+          swift build
+
+      - name: Check redirects
+        run: ./check-redirects.sh
+
+      - name: Check dependencies
+        run: ./check-dependencies.sh
+
+  test-validator-macOS:
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [macos-latest]
         swift: ["5.8"]
-    runs-on: ${{ matrix.os }}
+    runs-on: macos-latest
     steps:
       - uses: swift-actions/setup-swift@v1
         with: