fix(deps): update dependency pixelmatch to v6

Author: renovate[bot]

packages/cypress-plugin-visual-regression-diff/package.json

@@ -101,7 +101,7 @@
     "glob": "8.1.0",
     "meta-png": "1.0.6",
     "move-file": "2.1.0",
-    "pixelmatch": "5.3.0",
+    "pixelmatch": "6.0.0",
     "pngjs": "7.0.0",
     "sharp": "0.32.6"
   },