fix: use yamale v6 to work around bug (#747)

Author: eatondustin1

.github/workflows/helm-charts-test.yaml

@@ -31,6 +31,8 @@ jobs:
       - name: Install chart-testing tools
         id: lint
         uses: helm/chart-testing-action@v2
+        with:
+          yamale_version: '6.0.0'
 
       - name: Run chart-testing (list-changed)
         id: list-changed