Add logger gem to fix Ruby 4.0 deprecation warning

Ruby 3.4+ warns that logger will no longer be a default gem in Ruby 4.0.
Explicitly adding it to Gemfile prevents this warning:

'warning: logger was loaded from the standard library, but will
no longer be part of the default gems starting from Ruby 4.0.0.'

The logger gem is a dependency of excon (used by docker-api), but
it's being transitioned from a default gem to a regular gem.
By explicitly including it, we:
- Silence the deprecation warning
- Ensure forward compatibility with Ruby 4.0
- Make the dependency explicit rather than implicit

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

Author: chorrell

Gemfile

@@ -4,3 +4,7 @@ gem 'docker-api', '~> 2.4'
 gem 'rake', '~> 13.0'
 gem 'rspec', '~> 3.13'
 gem 'serverspec', '~> 2.43'
+
+# Explicitly include logger to avoid Ruby 4.0 deprecation warning
+# logger will no longer be a default gem in Ruby 4.0
+gem 'logger'

Gemfile.lock

@@ -7,6 +7,7 @@ GEM
       excon (>= 0.64.0)
       multi_json
     excon (0.109.0)
+    logger (1.7.0)
     multi_json (1.15.0)
     net-scp (4.1.0)
       net-ssh (>= 2.6.5, < 8.0.0)
@@ -47,6 +48,7 @@ PLATFORMS
 
 DEPENDENCIES
   docker-api (~> 2.4)
+  logger
   rake (~> 13.0)
   rspec (~> 3.13)
   serverspec (~> 2.43)