Move release dependencies to optionalDependencies.

Author: rwjblue

package.json

@@ -91,7 +91,9 @@
     "mocha": "^8.2.1",
     "module-name-inliner": "link:./tests/dummy/lib/module-name-inliner",
     "prettier": "^2.2.1",
-    "qunit-dom": "^1.5.0",
+    "qunit-dom": "^1.5.0"
+  },
+  "optionalDependencies": {
     "release-it": "^14.2.1",
     "release-it-lerna-changelog": "^3.1.0"
   },