Simplify CI: let SPM resolve SwiftSyntax version naturally

Remove sed-based version pinning that caused linker errors on Swift 6.2.
Swift 6.2 ships with prebuilt SwiftSyntax 602.0.0, and forcing an exact
version caused duplicate symbol errors during linking.

Each Swift version naturally resolves to compatible SwiftSyntax:
- Swift 6.0.x → SwiftSyntax 600.x
- Swift 6.1.x → SwiftSyntax 601.x
- Swift 6.2.x → SwiftSyntax 602.x

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: zhiqipan

.github/workflows/test.yml

@@ -63,24 +63,15 @@ jobs:
     name: Test BridgeJS against Swift versions
     strategy:
       matrix:
-        include:
-          - swift-image: "swift:6.0.3"
-            swift-syntax-version: "600.0.1"
-          - swift-image: "swift:6.1.2"
-            swift-syntax-version: "601.0.1"
-          - swift-image: "swift:6.2"
-            swift-syntax-version: "602.0.0"
+        swift-image:
+          - "swift:6.0.3"   # Tests with SwiftSyntax 600.x (non-SwiftSyntax602 code path)
+          - "swift:6.1.2"   # Tests with SwiftSyntax 601.x (non-SwiftSyntax602 code path)
+          - "swift:6.2"     # Tests with SwiftSyntax 602.x (SwiftSyntax602 code path)
     runs-on: ubuntu-latest
     container:
       image: ${{ matrix.swift-image }}
     steps:
       - uses: actions/checkout@v6
-      - name: Pin swift-syntax to exact version
-        working-directory: Plugins/BridgeJS
-        run: |
-          # Use exact version constraint to pin swift-syntax
-          sed -i 's/from: "600.0.1"/exact: "${{ matrix.swift-syntax-version }}"/' Package.swift
-          cat Package.swift | grep swift-syntax | head -1
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with: