build: change postinstall script to prepare so it runs only in development

Author: mrholek

package-lock.json

@@ -65,7 +65,7 @@
     "docs-serve-only": "npx sirv-cli _gh_pages --port 9001",
     "lockfile-lint": "lockfile-lint --allowed-hosts npm --allowed-schemes https: --empty-hostname false --type npm --path package-lock.json",
     "update-deps": "ncu -u -x eslint,karma-browserstack-launcher,karma-rollup-preprocessor",
-    "postinstall": "rimraf node_modules/sass",
+    "prepare": "rimraf node_modules/sass",
     "release": "npm-run-all dist release-sri docs-build release-zip*",
     "release-sri": "node build/generate-sri.mjs",
     "release-version": "node build/change-version.mjs",