Fix code style errors

Problem/Motivation

Pipelines should be green: https://git.drupalcode.org/project/ohdear_integration/-/pipelines

$ vendor/bin/phpcs -s $_WEB_ROOT/modules/custom --report-junit=junit.xml --report-full --report-summary --report-source $_PHPCS_EXTRA
FILE: ...hdear_integration/web/modules/custom/ohdear_integration/src/OhDearInfo.php
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FOUND 4 ERRORS AFFECTING 2 LINES
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 77 | ERROR | [x] Parameter $siteId has null default value, but is not marked
    |       |     as nullable.
    |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
 77 | ERROR | [x] Parameter $from has null default value, but is not marked as
    |       |     nullable.
    |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
 77 | ERROR | [x] Parameter $to has null default value, but is not marked as
    |       |     nullable.
    |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
 94 | ERROR | [x] Parameter $siteId has null default value, but is not marked
    |       |     as nullable.
    |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
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PHPCBF CAN FIX THE 4 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Time: 301ms; Memory: 6MB
PHP CODE SNIFFER REPORT SUMMARY
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FILE                                                            ERRORS  WARNINGS
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...on/web/modules/custom/ohdear_integration/src/OhDearInfo.php  4       0
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A TOTAL OF 4 ERRORS AND 0 WARNINGS WERE FOUND IN 10 FILES
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PHPCBF CAN FIX 4 OF THESE SNIFF VIOLATIONS AUTOMATICALLY
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PHP CODE SNIFFER VIOLATION SOURCE SUMMARY
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    SOURCE                                                                 COUNT
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[x] SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.Null  4
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A TOTAL OF 4 SNIFF VIOLATIONS WERE FOUND IN 1 SOURCE
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PHPCBF CAN FIX THE 1 MARKED SOURCES AUTOMATICALLY (4 VIOLATIONS IN TOTAL)
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