Fix GitHub builds on macOS

Add icu4c to PKG_CONFIG_PATH

Author: sgillespie

.github/workflows/haskell.yml

@@ -60,7 +60,7 @@ jobs:
       run: |
         brew install postgresql@14 libpq [email protected] tree
         tree /usr/local/opt/postgresql@14/lib/
-        echo "PKG_CONFIG_PATH=/usr/local/opt/postgresql@14/lib/postgresql@14/pkgconfig:/usr/local/opt/openssl/lib/pkgconfig:$PKG_CONFIG_PATH" | tee $GITHUB_ENV
+        echo "PKG_CONFIG_PATH=/usr/local/opt/icu4c/lib/pkgconfig:/usr/local/opt/postgresql@14/lib/postgresql@14/pkgconfig:/usr/local/opt/openssl/lib/pkgconfig:$PKG_CONFIG_PATH" | tee $GITHUB_ENV
 
     - name: Start Postgresql service (macOS)
       if: matrix.os == 'macos-latest'