ci/macos: silence brew warnings

.github/workflows/build.yml

@@ -106,13 +106,13 @@ jobs:
           )
           # Lua 5.1 is disabled, so we need to work around that:
           # - fetch all packages
-          brew fetch "${packages[@]}"
+          brew fetch --formula "${packages[@]}"
           # - disable auto-updates
           export HOMEBREW_NO_AUTO_UPDATE=1
           # - install lua@5.1 from cache
-          brew install "$(brew --cache lua@5.1)"
+          brew install --formula --quiet "$(brew --cache lua@5.1)"
           # - and install the rest
-          brew install "${packages[@]}"
+          brew install --formula --quiet "${packages[@]}"
 
       - name: Update PATH
         run: >