Remove staged linting for changelogs (#455)

The staged linting for changelogs fails on my device when multiple changelog files are staged. I suspect the `--file` flag of the `auto-changelog` CLI does not accept multiple files.

Even if that worked, we would have to conditionally pass the lint command the `--rc` flag for releases in order for it to pass / be useful, so the simplest solution seemed to be to remove it.

package.json

@@ -38,9 +38,6 @@
     ],
     "!(CHANGELOG).{json,yml,md}": [
       "prettier --write"
-    ],
-    "CHANGELOG.md": [
-      "auto-changelog validate --file"
     ]
   },
   "devDependencies": {