Update testing workflow to modify Package.resolved instead of workaro…

…und in Package.swift

.github/workflows/tests.yml

@@ -95,9 +95,12 @@ jobs:
     runs-on: macOS-14
     env:
       DEVELOPER_DIR: /Applications/Xcode_15.4.app/Contents/Developer
-      SWIFT_SYNTAX_REVISION: ${{ matrix.revision }}
     steps:
     - name: Checkout Repo
       uses: actions/checkout@v4
+    - name: Update Package Pins
+      run: |
+        jq '(.pins[] | select(.identity == "swift-syntax") | .state.revision) = "${{ matrix.revision }}" | (.pins[] | select(.identity == "swift-syntax") | .state.version) = "${{ matrix.swift-syntax }}"' Package.resolved | sed 's/": /" : /g' > Package.resolved.tmp && mv Package.resolved.tmp Package.resolved
+        git diff Package.resolved
     - name: Run Tests
       run: xcodebuild clean test -scheme XCStringsTool-Package -destination platform=macOS

Package.swift

@@ -170,12 +170,3 @@ if ProcessInfo.processInfo.environment.keys.contains("BENCHMARK_PACKAGE") {
         )
     )
 }
-
-// Support testing different versions of Swift Syntax
-if let revision = ProcessInfo.processInfo.environment["SWIFT_SYNTAX_REVISION"] {
-    // TODO: The `kind` symbol isn't available in Xcode 15.2? Check newer versions.
-    package.dependencies.removeAll(where: { $0.url == "https://github.com/swiftlang/swift-syntax" })
-    package.dependencies.append(
-        .package(url: "https://github.com/swiftlang/swift-syntax", revision: revision)
-    )
-}