Fix CI for ghcjs

Author: maksbotan

.github/workflows/ghcjs.yml

@@ -34,7 +34,7 @@ jobs:
     - name: Cabal update and freeze
       run: |
         cabal v2-update
-        cabal v2-freeze -w /opt/ghc/8.4.4/bin/ghc
+        cabal v2-freeze --ghcjs -w /opt/ghcjs/8.4/bin/ghcjs
 
     - uses: actions/[email protected]
       name: Cache ~/.cabal/store and dist-newstyle