[fix]Fix ruby version and update mimemagic

Gemfile

@@ -2,7 +2,7 @@
 
 source 'https://rubygems.org'
 
-ruby ENV['TRAVIS_RUBY_VERSION'] || '2.6.6'
+ruby ENV['TRAVIS_RUBY_VERSION'] || '~>2.6.6'
 
 # rails-assets requires >= 1.8.4
 if Gem::Version.new(Bundler::VERSION) < Gem::Version.new('1.8.4')
@@ -28,6 +28,7 @@ gem 'paper_trail'
 gem 'carrierwave'
 gem 'carrierwave-bombshelter'
 gem 'mini_magick'
+gem 'mimemagic', '~> 0.3.6'
 
 # for internationalizing
 gem 'rails-i18n'

Gemfile.lock

@@ -299,7 +299,9 @@ GEM
     mime-types (3.3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2021.0225)
-    mimemagic (0.3.6)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mina (1.2.3)
       open4 (~> 1.3.4)
       rake
@@ -721,6 +723,7 @@ DEPENDENCIES
   leaflet-rails
   letter_opener
   letter_opener_web (~> 1.0)
+  mimemagic (~> 0.3.6)
   mina
   mini_magick
   money-rails

app/views/conferences/show.html.haml

@@ -82,5 +82,3 @@
     - if @conference.contact.has_social_media?
       = render 'social_media', contact: @conference.contact
   = render 'footer'
-
-'test'