ci: run tests on node 20

Author: danielroe

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
       - run: corepack enable
       - uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
           cache: "pnpm"
       - run: pnpm install
       - run: pnpm lint