Remove unused environment variable

Author: marijnvanwezel

.github/workflows/main.yml

@@ -27,7 +27,6 @@ jobs:
       COMPOSER_VERSION: 2
       INSTALL_PATH: php-cypher-dsl
       REPOSITORY_NAME: php-cypher-dsl
-      FIXER_RULES: "@PSR12,align_multiline_comment,array_indentation,blank_line_before_statement,no_unused_imports,no_useless_else,no_useless_return,ordered_imports,phpdoc_scalar,return_assignment,simplified_if_return,trailing_comma_in_multiline"
 
     steps:
       # https://getcomposer.org/download/