updating changelog; removing ruby-head from travis matrix

Author: gaorlov

.travis.yml

@@ -48,12 +48,6 @@ matrix:
       gemfile: gemfiles/4.1.gemfile
     - rvm: 2.6.0
       gemfile: gemfiles/4.2.gemfile
-    - rvm: ruby-head
-      gemfile: gemfiles/4.0.gemfile
-    - rvm: ruby-head
-      gemfile: gemfiles/4.1.gemfile
-    - rvm: ruby-head
-      gemfile: gemfiles/4.2.gemfile
 # We need to install latest version of bundler, because one in travis
 # image is too old to recognize platform => :mri_22 in Gemfile.
 before_install:

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+## 1.15.0
+
+- [#346](https://github.com/JsonApiClient/json_api_client/pull/346) - add the option to have immutable resources
 - [#357](https://github.com/JsonApiClient/json_api_client/pull/357) - fix missing constant formatter
 
 ## 1.14.1