fix!: composer.json and composer.lock have been removed from default …

…package and bump files.

- No need to bump version for `composer` as it relies on VCS tag to infer version (#495)
- Closes #394

BREAKING CHANGE: `composer.json` and `composer.lock` will no longer be read from or bumped by default. If you need to obtain a version or write a version to these files, please use `bumpFiles` and/or `packageFiles` options accordingly.

defaults.js

@@ -32,14 +32,12 @@ defaults.header = '# Changelog\n\nAll notable changes to this project will be do
 defaults.packageFiles = [
   'package.json',
   'bower.json',
-  'manifest.json',
-  'composer.json'
+  'manifest.json'
 ]
 
 defaults.bumpFiles = defaults.packageFiles.concat([
   'package-lock.json',
-  'npm-shrinkwrap.json',
-  'composer.lock'
+  'npm-shrinkwrap.json'
 ])
 
 module.exports = defaults