Add logger to gem dependencies

Logger is being kicked out of core Ruby and is now a standalone gem.

Author: wconrad

Gemfile.lock

@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     ftpd (2.1.0)
+      logger (~> 1.6)
       memoizer (~> 1.0)
 
 GEM
@@ -37,6 +38,7 @@ GEM
     date (3.4.1)
     diff-lcs (1.6.0)
     ffi (1.17.1)
+    logger (1.6.6)
     memoizer (1.0.3)
     mini_mime (1.1.5)
     multi_test (1.1.0)

ftpd.gemspec

@@ -79,6 +79,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 2.7.8"
   s.rubygems_version = "2.5.1"
   s.summary = "Pure Ruby FTP server library"
+  s.add_runtime_dependency("logger", "~> 1.6")
   s.add_runtime_dependency("memoizer", "~> 1.0")
   s.add_development_dependency("net-ftp", "~> 0.3")
   s.add_development_dependency("cucumber", "~> 9.1")