Update GH actions artifact to v4

Author: carbolymer

.github/workflows/haskell.yml

@@ -118,7 +118,7 @@ jobs:
 
           tar zcvf artifacts-${{ runner.OS }}-${{ matrix.ghc }}.tar.gz artifacts
 
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: artifacts-${{ runner.OS }}-${{ matrix.ghc }}.tar.gz
           path: artifacts-${{ runner.OS }}-${{ matrix.ghc }}.tar.gz
@@ -226,7 +226,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
 
     steps:
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
         id: download_artifact
         with:
           name: artifacts-${{ runner.OS }}-${{ matrix.ghc }}.tar.gz