Pin dependency @rollup/plugin-json to 6.0.0

Author: renovate[bot]

package-lock.json

@@ -47,7 +47,7 @@
     "@cloudfour/eslint-plugin": "21.1.0",
     "@etchteam/storybook-addon-status": "4.2.2",
     "@rollup/plugin-babel": "6.0.3",
-    "@rollup/plugin-json": "^6.0.0",
+    "@rollup/plugin-json": "6.0.0",
     "@rollup/plugin-node-resolve": "13.3.0",
     "@storybook/addon-a11y": "6.5.9",
     "@storybook/addon-docs": "6.5.9",