Ensure haml-lint checks Syntax

Also ensures we check Syntax with RuboCop, which is different.

.haml-lint.yml

@@ -118,7 +118,6 @@ linters:
       - Lint/ParenthesesAsGroupedExpression
       - Lint/RedundantWithIndex
       - Lint/SafeNavigationConsistency
-      - Lint/Syntax
       - Metrics/BlockNesting
       - Naming/VariableName
       - Performance/RedundantMatch
@@ -155,6 +154,9 @@ linters:
     enabled: true
     style: space
+  Syntax:
+    enabled: true
+
   Indentation:
     enabled: true
     character: space  # or tab