ci: update Node.js version to 20

Author: FliPPeDround

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        node_version: [18, 20]
+        node_version: [20]
       fail-fast: false
 
     steps: