Use checkout v4

Author: adam-fowler

.github/workflows/ci.yml

@@ -67,5 +67,5 @@ jobs:
         with:
           branch: swift-5.10-release
           tag: 5.10-RELEASE
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: swift test

Tests/JMESPathTests/ComplianceTests.swift

@@ -6,10 +6,9 @@
 //
 
 import Foundation
+import JMESPath
 import XCTest
 
-@testable import JMESPath
-
 #if os(Linux) || os(Windows)
     import FoundationNetworking
 #endif