.eslintrc.json: use jsonc/no-irregular-whitespace

The eslint-plugin-jsonc documentation recommends turning ESLint's
no-irregular-whitespace plugin off for JSON files in favor of its
own jsonc/no-irregular-whitespace plugin.

See: https://ota-meshi.github.io/eslint-plugin-jsonc/rules/no-irregular-whitespace.html

.eslintrc.json

@@ -234,7 +234,9 @@
         "plugin:jsonc/recommended-with-json5"
       ],
       "rules": {
-        "no-irregular-whitespace": "error",
+        // ESLint core no-irregular-whitespace rule doesn't work well in JSON
+        "no-irregular-whitespace": "off",
+        "jsonc/no-irregular-whitespace": "error",
         "no-trailing-spaces": "error",
         "jsonc/comma-dangle": [
           "error",