Set include and link dirs explicitly for macOS

.github/workflows/test-libmaxminddb.yml

@@ -45,13 +45,27 @@ jobs:
         if: matrix.platform == 'ubuntu-latest'
 
       - name: Install libmaxminddb
-        run: brew install libmaxminddb
+        run: brew install libmaxminddb && brew ls --verbose libmaxminddb
         if: matrix.platform == 'macos-latest'
 
-      - name: Build with Werror and Wall
+      - name: Build with Werror and Wall (not macOS)
         run: python setup.py build
+        if: matrix.platform != 'macos-latest'
         env:
           CFLAGS: "-Werror -Wall -Wextra"
 
+      # Starting at the end of April 2024, the homebrew include and lib
+      # directories were not properly set up in the flags for the GitHub
+      # images. I looked for an issue both in Homebrew and actions/runner-images
+      # and did not find one or similar reports from other users. Setting
+      # them here seemed easier than digging into it further. It would
+      # probably be worth trying to remove this in the future.
+      - name: Build with Werror and Wall (macOS)
+        run: python setup.py build
+        if: matrix.platform == 'macos-latest'
+        env:
+          CFLAGS: "-Werror -Wall -Wextra -I/opt/homebrew/include"
+          LDFLAGS: "-L/opt/homebrew/lib"
+
       - name: Test with tox (system libmaxminddb)
         run: tox