update a few dependencies

Gemfile.lock

@@ -10,9 +10,8 @@ GEM
     diff-lcs (1.3)
     docile (1.1.5)
     json (2.1.0)
-    rake (12.0.0)
+    rake (12.3.1)
     rdoc (5.1.0)
-    redcarpet (3.4.0)
     rspec (3.6.0)
       rspec-core (~> 3.6.0)
       rspec-expectations (~> 3.6.0)
@@ -31,7 +30,7 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    yard (0.9.9)
+    yard (0.9.12)
 
 PLATFORMS
   ruby
@@ -40,11 +39,10 @@ PLATFORMS
 DEPENDENCIES
   rake
   rdoc
-  redcarpet
   rscons!
   rspec
   simplecov
   yard
 
 BUNDLED WITH
-   1.15.4
+   1.16.1

rscons.gemspec

@@ -25,5 +25,4 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "simplecov"
   gem.add_development_dependency "yard"
   gem.add_development_dependency "rdoc"
-  gem.add_development_dependency "redcarpet"
 end