Remove development dependency on logging-journald

In d0cae6e the logging stack was
replaced, but this was only for smart_proxy_dynflow_core. That's now
dropped and smart-proxy itself has the logging dependencies. Removing
this simplifies the dependencies.

.github/workflows/ruby.yml

@@ -8,8 +8,6 @@ jobs:
   rubocop:
     runs-on: ubuntu-latest
     steps:
-      - run: sudo apt-get update
-      - run: sudo apt-get install build-essential libsystemd-dev
       - uses: actions/checkout@v2
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
@@ -28,8 +26,6 @@ jobs:
       matrix:
         ruby-version: [2.5, 2.7]
     steps:
-      - run: sudo apt-get update
-      - run: sudo apt-get install build-essential libsystemd-dev
       - uses: actions/checkout@v2
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1

Gemfile

@@ -24,7 +24,6 @@ group :test do
   gem 'webmock'
 end
 
-gem 'logging-journald', '~> 2.0', :platforms => [:ruby], :require => false
 gem 'rack', '>= 1.1'
 gem 'sinatra'