Update Asciidoctor extension dependency

Asciidoctor already handles the caching so we don't really need to. On
the plus side, it gives some choice whether the pipeline should have a
cache or not.

asciidoctor-foodogsquared-extensions.gemspec

@@ -16,6 +16,5 @@ Gem::Specification.new do |s|
   s.files         = Dir['lib/**/*', '*.gemspec']
 
   s.add_runtime_dependency 'asciidoctor', '~> 2.0'
-  s.add_runtime_dependency 'open-uri-cached', '~> 1.0'
   s.add_runtime_dependency 'rugged', '~> 1.0'
 end

lib/asciidoctor/fdroid-link-inline-macro/extension.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require 'open-uri'
-require 'open-uri/cached'
 require 'yaml'
 
 class FDroidLinkInlineMacro < Asciidoctor::Extensions::InlineMacroProcessor

lib/asciidoctor/flathub-link-inline-macro/extension.rb

@@ -2,7 +2,6 @@
 
 require 'json'
 require 'open-uri'
-require 'open-uri/cached'
 
 class FlathubLinkInlineMacro < Asciidoctor::Extensions::InlineMacroProcessor
   use_dsl

lib/asciidoctor/github-raw-content-include-processor/extension.rb

@@ -3,7 +3,6 @@
 require 'base64'
 require 'json'
 require 'open-uri'
-require 'open-uri/cached'
 require 'uri'
 
 class GitHubRawIncludeProcessor < Asciidoctor::Extensions::IncludeProcessor

lib/asciidoctor/gitlab-raw-content-include-processor/extension.rb

@@ -3,7 +3,6 @@
 require 'base64'
 require 'json'
 require 'open-uri'
-require 'open-uri/cached'
 require 'uri'
 
 class GitLabRawIncludeProcessor < Asciidoctor::Extensions::IncludeProcessor

lib/asciidoctor/musicbrainz-link-inline-macro/extension.rb

@@ -2,7 +2,6 @@
 
 require 'json'
 require 'open-uri'
-require 'open-uri/cached'
 require 'uri'
 
 class MusicBrainzLinkInlineMacro < Asciidoctor::Extensions::InlineMacroProcessor

lib/asciidoctor/swhid-include-processor/extension.rb

@@ -2,7 +2,6 @@
 
 require 'json'
 require 'open-uri'
-require 'open-uri/cached'
 require 'uri'
 
 class SWHIDIncludeProcessor < Asciidoctor::Extensions::IncludeProcessor