ci: pin swift 6.2 toolchain

Author: Dimillian

.github/workflows/ci.yml

@@ -9,6 +9,10 @@ jobs:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v4
+      - name: Set up Swift 6.2
+        uses: swift-actions/setup-swift@v2
+        with:
+          swift-version: "6.2"
       - name: Build
         run: swift build
       - name: Test