Attempt to remove listen and ruby_dep dependencies.

Causing warnings due to conditional logic in gemspec.
Also don't seem to be used.

Gemfile.lock

@@ -10,11 +10,7 @@ GEM
     coderay (1.1.3)
     diff-lcs (1.4.4)
     docile (1.3.5)
-    ffi (1.12.2)
     json (2.5.1)
-    listen (3.0.8)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
     method_source (1.0.0)
     parallel (1.13.0)
     parser (2.7.2.0)
@@ -26,9 +22,6 @@ GEM
     rainbow (2.2.2)
       rake
     rake (12.3.3)
-    rb-fsevent (0.10.4)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
     rspec (3.10.0)
       rspec-core (~> 3.10.0)
       rspec-expectations (~> 3.10.0)
@@ -52,7 +45,6 @@ GEM
     rubocop-rspec (1.5.1)
       rubocop (>= 0.41.2)
     ruby-progressbar (1.11.0)
-    ruby_dep (1.3.1)
     simplecov (0.17.1)
       docile (~> 1.1)
       json (>= 1.8, < 3)
@@ -65,13 +57,11 @@ PLATFORMS
 
 DEPENDENCIES
   bundler
-  listen (~> 3.0.8)
   pry
   retriable!
   rspec
   rubocop (>= 0.50, < 0.51)
   rubocop-rspec
-  ruby_dep (~> 1.3.1)
   simplecov
 
 BUNDLED WITH

retriable.gemspec

@@ -23,10 +23,4 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rspec", "~> 3"
 
-  if RUBY_VERSION < "2.3"
-    spec.add_development_dependency "ruby_dep", "~> 1.3.1"
-    spec.add_development_dependency "listen", "~> 3.0.8"
-  else
-    spec.add_development_dependency "listen", "~> 3.1"
-  end
 end