ci: use Swift container for swift-format to fix GPG issues

Author: coenttb

.github/workflows/swift-format.yml

@@ -13,16 +13,12 @@ jobs:
   swift_format:
     name: swift-format
     runs-on: ubuntu-latest
+    container: swift:6.0
     permissions:
       contents: write
     steps:
       - uses: actions/checkout@v5
 
-      - name: Setup Swift
-        uses: swift-actions/setup-swift@v2
-        with:
-          swift-version: '6.0'
-
       - name: Cache swift-format
         id: cache-swift-format
         uses: actions/cache@v4
@@ -36,7 +32,7 @@ jobs:
           git clone --depth 1 --branch main https://github.com/apple/swift-format.git
           cd swift-format
           swift build -c release
-          sudo cp .build/release/swift-format /usr/local/bin/
+          cp .build/release/swift-format /usr/local/bin/
           cd ..
           rm -rf swift-format