Update CI

Author: thomashoneyman

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Set up a PureScript toolchain
         uses: purescript-contrib/setup-purescript@main