Replace deprecated code

------ --------------------------------------------------
Line country.module
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18 Call to deprecated method url() of class Drupal.
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------ -----------------------------------------------------------------------------------
Line src/Controller/CountryAutocompleteController.php
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43 \Drupal calls should be avoided in classes, use dependency injection instead
45 Call to deprecated method strtolower() of class Drupal\Component\Utility\Unicode.
45 Call to deprecated method strtolower() of class Drupal\Component\Utility\Unicode.
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------ ------------------------------------------------------------------------------
Line src/CountryManager.php
------ ------------------------------------------------------------------------------
35 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

------ ------------------------------------------------------------------------------
Line src/Plugin/Field/FieldFormatter/CountryDefaultFormatter.php
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34 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

------ ------------------------------------------------------------------------------
Line src/Plugin/Field/FieldWidget/CountryAutocompleteWidget.php
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44 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

------ ------------------------------------------------------------------------------
Line src/Plugin/Field/FieldWidget/CountryDefaultWidget.php
------ ------------------------------------------------------------------------------
32 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

------ ------------------------------------------------------------------------------
Line src/Plugin/views/filter/CountryItem.php
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173 \Drupal calls should be avoided in classes, use dependency injection instead
174 \Drupal calls should be avoided in classes, use dependency injection instead
------ ------------------------------------------------------------------------------

I might be able to help with a patch later if someone doesn't fix it first :)