deps: update rake requirement from ~> 13.1.0 to ~> 13.2.1 (#81)

Updates the requirements on [rake](https://github.com/ruby/rake) to permit the latest version.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v13.1.0...v13.2.1)

---
updated-dependencies:
- dependency-name: rake
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -67,7 +67,7 @@ GEM
     public_suffix (5.0.4)
     racc (1.7.3)
     rainbow (3.1.1)
-    rake (13.1.0)
+    rake (13.2.1)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
@@ -121,7 +121,7 @@ PLATFORMS
 DEPENDENCIES
   bundler
   jekyll-post-image-generator!
-  rake (~> 13.1.0)
+  rake (~> 13.2.1)
   rspec (~> 3.0)
   rubocop
 

jekyll-post-image-generator.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'mini_magick', '>= 4.11.0'
 
   spec.add_development_dependency 'bundler'
-  spec.add_development_dependency 'rake', '~> 13.1.0'
+  spec.add_development_dependency 'rake', '~> 13.2.1'
   spec.add_development_dependency 'rspec', '~> 3.0'
   spec.add_development_dependency 'rubocop'
 end