Add imgSnapshotTest for escaped quotes

cypress/integration/rendering/flowchart.spec.js

@@ -901,4 +901,10 @@ graph TD
       { htmlLabels: true, flowchart: { htmlLabels: true }, securityLevel: 'loose' }
     );
   });
+  it('67: allow escaping quotes with backslash', () => {
+    imgSnapshotTest(`
+      graph TD
+        a_node("This has an escaped \\" in it") -- "edge string can escape too \\"" --> b_node
+    `);
+  });
 });