Meta tweaks

Author: sindresorhus

.github/workflows/main.yml

@@ -13,8 +13,8 @@ jobs:
           - 20
           - 18
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/setup-node@v3
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
       - run: npm install

package.json

@@ -15,6 +15,7 @@
 		"github-markdown-css": "./cli.js"
 	},
 	"exports": "./index.js",
+	"sideEffects": false,
 	"engines": {
 		"node": ">=18"
 	},