ci: bump checkout pin on lint workflows and drop stale scheme testable

The SwiftLint and SwiftFormat workflows were the only two of 26 still pinned
to actions/checkout v3.5.3, which runs on the deprecated Node 16 runtime.
Bumped both to the v4.1.1 pin the other 24 workflows already use.

Also removed the AmplifyConnectClientIntegrationTests testable from
Amplify-Package.xcscheme. That target does not exist in Package.swift — the
integration tests live in a separate host-app project
(AmplifyClients/AmplifyConnectClient/Tests/ConnectClientHostApp) where the
scheme is named ConnectClientIntegrationTests. This was harmless only because
Amplify-Package is used for `xcodebuild build` and never `test`; it would fail
for anyone invoking the scheme's test action. Verified the scheme is still
valid XML.

Author: harsh62

.github/workflows/swiftformat.yml

@@ -28,7 +28,7 @@ jobs:
       SWIFTFORMAT_VERSION: '0.60.1'
       SWIFTFORMAT_SHA256: 'cb4738085cf39c08da00b79b4a3683e77458ca12909934d04e5087d8e73f5e43'
     steps:
-      - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 #v3.5.3
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 #v4.1.1
         with:
           persist-credentials: false
 

.github/workflows/swiftlint.yml

@@ -27,7 +27,7 @@ jobs:
     container:
       image: ghcr.io/realm/swiftlint:0.54.0
     steps:
-      - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 #v3.5.3
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 #v4.1.1
         with:
           persist-credentials: false
 

.swiftpm/xcode/xcshareddata/xcschemes/Amplify-Package.xcscheme

@@ -895,16 +895,6 @@
                ReferencedContainer = "container:">
             </BuildableReference>
          </TestableReference>
-         <TestableReference
-            skipped = "NO">
-            <BuildableReference
-               BuildableIdentifier = "primary"
-               BlueprintIdentifier = "AmplifyConnectClientIntegrationTests"
-               BuildableName = "AmplifyConnectClientIntegrationTests"
-               BlueprintName = "AmplifyConnectClientIntegrationTests"
-               ReferencedContainer = "container:">
-            </BuildableReference>
-         </TestableReference>
       </Testables>
    </TestAction>
    <LaunchAction