Fix Actions on MacOS Latest

Author: martell

.github/workflows/ci.yml

@@ -76,10 +76,11 @@ jobs:
           echo '::set-env name=MYSQL_EXAMPLE_DATABASE_URL::mysql://root:root@localhost/diesel_example'
           echo '::set-env name=MYSQL_UNIT_TEST_DATABASE_URL::mysql://root:root@localhost/diesel_unit_test'
 
-      - name: Install postgres (MacOs)
+      - name: Install postgres (MacOS)
         if: runner.os == 'macOS' && matrix.backend == 'postgres'
         run: |
           brew update
+          brew uninstall --ignore-dependencies libpq
           brew install postgres
           /usr/local/opt/postgres/bin/pg_ctl -D /usr/local/var/postgres start
           sleep 3