Update php-cs-fixer to 2.17.3

.github/workflows/continuous-integration.yaml

@@ -14,7 +14,7 @@ jobs:
           php-version: '7.2'
           coverage: 'none'
           extensions: 'json, mbstring, tokenizer'
-          tools: 'composer-normalize:2.11.0, php-cs-fixer:2.16.7'
+          tools: 'composer-normalize:2.11.0, php-cs-fixer:2.17.3'
 
       - name: 'Check PHP code'
         run: |

phive.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phive xmlns="https://phar.io/phive">
-  <phar name="php-cs-fixer" version="^2.16" installed="2.16.7" location="./tools/php-cs-fixer.phar" copy="true"/>
+  <phar name="php-cs-fixer" version="^2.17" installed="2.17.3" location="./tools/php-cs-fixer.phar" copy="true"/>
   <phar name="php-coveralls" version="^2.2" installed="2.2.0" location="./tools/php-coveralls.phar" copy="true"/>
 </phive>