fix: update test filter names in CI workflows

Author: csjones

.github/workflows/pr.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Run test suite
-        run: swift test --filter "SubtreeTests"
+        run: swift test --filter "SubtreeLibTests"
 
   linux:
     name: Test on Linux
@@ -30,4 +30,4 @@ jobs:
       - name: Run Linux test suite
         run: |
           docker run --rm -v "$(pwd):/workspace" -w /workspace swift:6.1 \
-            bash -c "swift package resolve && swift test --filter 'SubtreeTests'"
+            bash -c "swift package resolve && swift test --filter 'SubtreeLibTests'"