Drupal calls should be avoided in classes, use dependency injection instead

Problem/Motivation

FILE: ...les/contrib/gravitas_countdown/src/Plugin/Block/GravitasCountdownBlock.php
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FOUND 0 ERRORS AND 31 WARNINGS AFFECTING 31 LINES
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149 | WARNING | File::load calls should be avoided in classes, use dependency
| | injection instead
156 | WARNING | File::load calls should be avoided in classes, use dependency
| | injection instead
175 | WARNING | File::load calls should be avoided in classes, use dependency
| | injection instead
190 | WARNING | File::load calls should be avoided in classes, use dependency
| | injection instead
219 | WARNING | \Drupal calls should be avoided in classes, use dependency
| | injection instead
224 | WARNING | File::load calls should be avoided in classes, use dependency
| | injection instead
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Steps to reproduce

Execute the command: phpcs --standard=Drupal,DrupalPractice --extensions=php,module,inc,install,test,profile,theme,css,js,info,txt,md,yml,twig gravitas_countdown/

Proposed resolution

Add dependency injections.