CI: Remove "clean up" macOS workflow step

GitHub macOS runners no longer seem to have icu4c pre-installed

Author: sgillespie

.github/workflows/haskell.yml

@@ -43,11 +43,6 @@ jobs:
           minimal: false
           # enable IOG-full flavour to bring in all the crypto libraries we need.
           iog-full: true
-      - name: "macOS: clean up pre-installed libraries"
-        if: runner.os == 'macOS'
-        # Homebrew's icu4c conflics with Nix's
-        run: |
-          brew uninstall --ignore-dependencies icu4c
       - name: cache cabal
         uses: actions/cache@v3
         with: