Strict types support

[millnut]

With Drupal core moving towards strict types, more info I've added a test pipeline in preparation localgovdrupal/localgov_project#153 which has highlighted some failures which we should fix.

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  Line   modules/contrib/localgov_search/modules/localgov_search_db/tests/Kernel/InstallTest.php  
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  34     Call to method Drupal\KernelTests\KernelTestBase::setUp() with                           
         incorrect case: setup                                                                    
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  Line   modules/contrib/localgov_search/tests/src/Kernel/ContentTypesAddedToSearchTest.php  
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  39     Call to method Drupal\KernelTests\KernelTestBase::setUp() with                      
         incorrect case: setup                                                               
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