Remove Ruby version and constraints from dependencies from Gemfile.lock

- It's better to have the Ruby version in a single place for single source of truth

- Use the Gemfile.lock to manage the versions instead which should make it easier
to upgrade as it allows bundler a wider set of versions to resolve the dependencies.

Gemfile

@@ -1,28 +1,26 @@
 source "https://rubygems.org"
 
-ruby File.read(".ruby-version").chomp
-
-gem "activesupport", "~> 5.2"
-gem "capybara", "~> 3.33.0"
-gem "ffi", "1.12"
+gem "activesupport"
+gem "capybara"
+gem "ffi"
 gem "rake"
-gem "rspec", "~> 3.9"
+gem "rspec"
 gem "rubocop-govuk"
 gem "simplecov"
-gem "webmock", "~> 3.8"
+gem "webmock"
 
 gem "govuk_tech_docs"
-gem "middleman", "~> 4.3.11"
-gem "middleman-search_engine_sitemap", "~> 1.4"
+gem "middleman"
+gem "middleman-search_engine_sitemap"
 
 gem "github-markdown"
 gem "html-pipeline"
-gem "kramdown", "~> 2.3.0"
-gem "mdl", "~> 0.9.0"
+gem "kramdown"
+gem "mdl"
 
-gem "govuk_schemas", "~> 4.1.1"
+gem "govuk_schemas"
 
 # GitHub API
-gem "faraday-http-cache", "~> 2.2.0"
-gem "faraday_middleware", "~> 1.0.0"
-gem "octokit", "~> 4.18.0"
+gem "faraday-http-cache"
+gem "faraday_middleware"
+gem "octokit"

Gemfile.lock

@@ -284,28 +284,25 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  activesupport (~> 5.2)
-  capybara (~> 3.33.0)
-  faraday-http-cache (~> 2.2.0)
-  faraday_middleware (~> 1.0.0)
-  ffi (= 1.12)
+  activesupport
+  capybara
+  faraday-http-cache
+  faraday_middleware
+  ffi
   github-markdown
-  govuk_schemas (~> 4.1.1)
+  govuk_schemas
   govuk_tech_docs
   html-pipeline
-  kramdown (~> 2.3.0)
-  mdl (~> 0.9.0)
-  middleman (~> 4.3.11)
-  middleman-search_engine_sitemap (~> 1.4)
-  octokit (~> 4.18.0)
+  kramdown
+  mdl
+  middleman
+  middleman-search_engine_sitemap
+  octokit
   rake
-  rspec (~> 3.9)
+  rspec
   rubocop-govuk
   simplecov
-  webmock (~> 3.8)
-
-RUBY VERSION
-   ruby 2.6.6
+  webmock
 
 BUNDLED WITH
-   1.17.2
+   1.17.3