meson CI: simplify brew installs

expat is keg-only, so no need to install. curl and brotli are
preinstalled. python seems to have been updated with a new version that
doesn't work anymore with pip install.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

.github/workflows/on_PR_meson.yaml

@@ -137,8 +137,7 @@ jobs:
 
       - name: Install packages
         run: |
-          brew install curl brotli inih expat googletest
-          python3 -m pip install meson==0.54.1 ninja
+          brew install inih meson
 
       - name: Compile and Test
         run: |