Upgrade coding-standard dependency

[peter279k]

Changed log

• Running the php ~/composer.phar require imbo/imbo-coding-standard:^2.1 --dev command to upgrade the coding standard dependency.
• It can avoid the following error message when running the PHP-CS-Fixer action with the coding standard ^2.0 version:

> php-cs-fixer fix --dry-run --diff
Loaded config Imbo from "/home/localadmin/imboclient-php/.php-cs-fixer.php".

In FixerFactory.php line 180:

  Rule contains conflicting fixers:
  - "blank_lines_before_namespace" with "no_blank_lines_before_namespace"


fix [--path-mode PATH-MODE] [--allow-risky ALLOW-RISKY] [--config CONFIG] [--dry-run] [--rules RULES] [--using-cache USING-CACHE] [--cache-file CACHE-FILE] [--diff] [--format FORMAT] [--stop-on-violation] [--show-progress SHOW-PROGRESS] [--] [<path>...]

Script php-cs-fixer fix --dry-run --diff handling the cs event returned with error code 1