CI: fix Mac build

Author: AshleyYakeley

.github/workflows/ci.yml

@@ -14,10 +14,10 @@ jobs:
         ghc: ['9.8.2', '9.6.4', '9.4.8']
     steps:
     - uses: actions/checkout@v4
-    - name: "MacOS: install autotools"
+    - name: "MacOS: install autoconf"
       if: runner.os == 'macOS'
       run: |
-        brew install automake
+        brew install autoconf
     - uses: haskell-actions/setup@v2
       id: setup-haskell-cabal
       with: