Making acm_exception D9 ready

[joshirohit100]

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  Line   src/EventSubscriber/RouteExceptionEventSubscriber.php
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  21     \Drupal calls should be avoided in classes, use dependency injection instead
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  Line   src/EventSubscriber/RouteExceptionSubscriber.php
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  28     \Drupal calls should be avoided in classes, use dependency injection instead
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  Line   src/RouteExceptionHandler.php
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  51     Call to deprecated function drupal_set_message().
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[joshirohit100]

PR - #152