Removed Swift 5.9 support, and stopped running the now non-existent t…

…ests.

There were never actually any tests - just an empty stub that did nothing.

.github/workflows/swift.yml

@@ -8,20 +8,16 @@ on:
 
 jobs:
   build:
-    name: Swift ${{ matrix.swift }} on ${{ matrix.os }}
+    name: Swift on ${{ matrix.os }}
+
     strategy:
       matrix:
         os: [macos-latest]
-        swift: ["5.9", "5.10"]
 
     runs-on: ${{ matrix.os }}
 
     steps:
     - uses: swift-actions/setup-swift@v2
-      with:
-        swift-version: ${{ matrix.swift }}
     - uses: actions/checkout@v2
     - name: Build
       run: swift build
-    - name: Run tests
-      run: swift test