Fix failing build on CI on MacOs (#64)

After the last change it seems the CI is failing on MacOs (not sure why
it wasn't caught in PR CI).

Author: mmanela

.github/workflows/test.yml

@@ -14,7 +14,10 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-dotnet@v3
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: |
+            6.x
+            7.x
+            8.x
       - run: dotnet format --verify-no-changes
       - run: dotnet format --verify-no-changes
         working-directory: snapshots/input/syntax
@@ -28,5 +31,8 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-dotnet@v3
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: |
+            6.x
+            7.x
+            8.x
       - run: dotnet test