Fix a CI failure caused by installing libpg5 in Ruby 2.0 to 2.3 envir…

…onment

Fixed an issue where the process to downgrade libpq5 failed in CI for Ruby 2.0 to 2.3 environments.

ref: [Merge pull request collectiveidea#243 from collectiveidea/prepare-4-1-11 · collectiveidea/delayed_job_active_record@e5b4fbf](https://github.com/collectiveidea/delayed_job_active_record/actions/runs/11758646036/job/32757241087)

.github/workflows/ci.yml

@@ -237,7 +237,7 @@ jobs:
     - name: Reinstall libpg
       if: ${{ matrix.ruby < '2.4' && contains(matrix.gemfile, 'postgresql') }}
       # version located via https://pkgs.org/search/?q=libpq5 and the Ubuntu 20.04 LTS package list
-      run: sudo apt-get update && sudo apt-get install -y --allow-downgrades libpq5=12.19-0ubuntu0.20.04.1 && sudo apt-get install -y --allow-downgrades libpq-dev
+      run: sudo apt-get update && sudo apt-get install -y --allow-downgrades libpq5=12.2-4 && sudo apt-get install -y --allow-downgrades libpq-dev
     - uses: ruby/setup-ruby@v1
       env:
         BUNDLE_GEMFILE: ${{ matrix.gemfile }}