bump icalendar

Gemfile.lock

@@ -128,7 +128,7 @@ PATH
   remote: modules/meeting
   specs:
     openproject-meeting (8.2.1)
-      icalendar (~> 2.3.0)
+      icalendar (~> 2.5.0)
 
 PATH
   remote: modules/my_project_page
@@ -462,7 +462,9 @@ GEM
       concurrent-ruby (~> 1.0)
     i18n-js (3.2.0)
       i18n (>= 0.8.0, < 2)
-    icalendar (2.3.0)
+    icalendar (2.5.2)
+      ice_cube (~> 0.16)
+    ice_cube (0.16.3)
     ice_nine (0.11.2)
     interception (0.5)
     io-like (0.3.0)

modules/meeting/openproject-meeting.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |s|
   s.files = Dir['{app,config,db,lib,doc}/**/*', 'README.md']
   s.test_files = Dir['spec/**/*']
 
-  s.add_dependency 'icalendar', '~> 2.3.0'
+  s.add_dependency 'icalendar', '~> 2.5.0'
 
   s.add_development_dependency 'factory_girl_rails', '~> 4.0'
 end