Address PHPCS test failure

Problem/Motivation

FILE: ...r_expire-3491734/web/modules/custom/user_expire-3491734/user_expire.module
--------------------------------------------------------------------------------
FOUND 2 ERRORS AFFECTING 2 LINES
--------------------------------------------------------------------------------
 211 | ERROR | [x] Parameter $expiration has null default value, but is not
     |       |     marked as nullable.
     |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
 279 | ERROR | [x] Parameter $account has null default value, but is not marked
     |       |     as nullable.
     |       |     (SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.NullabilityTypeMissing)
--------------------------------------------------------------------------------
PHPCBF CAN FIX THE 2 MARKED SNIFF VIOLATIONS AUTOMATICALLY
--------------------------------------------------------------------------------
Time: 209ms; Memory: 6MB
PHP CODE SNIFFER REPORT SUMMARY
--------------------------------------------------------------------------------
FILE                                                            ERRORS  WARNINGS
--------------------------------------------------------------------------------
...4/web/modules/custom/user_expire-3491734/user_expire.module  2       0
--------------------------------------------------------------------------------
A TOTAL OF 2 ERRORS AND 0 WARNINGS WERE FOUND IN 7 FILES
--------------------------------------------------------------------------------
PHPCBF CAN FIX 2 OF THESE SNIFF VIOLATIONS AUTOMATICALLY
--------------------------------------------------------------------------------
PHP CODE SNIFFER VIOLATION SOURCE SUMMARY
--------------------------------------------------------------------------------
    SOURCE                                                                 COUNT
--------------------------------------------------------------------------------
[x] SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.Null  2
--------------------------------------------------------------------------------
A TOTAL OF 2 SNIFF VIOLATIONS WERE FOUND IN 1 SOURCE
--------------------------------------------------------------------------------
PHPCBF CAN FIX THE 1 MARKED SOURCES AUTOMATICALLY (2 VIOLATIONS IN TOTAL)
--------------------------------------------------------------------------------

Steps to reproduce

Run PHPCS tests

Proposed resolution

1. Fix the broken test
2. Configure gitlab to not allow merging if phpcs job doesn't pass.

phpcs:
  allow_failure: false

Remaining tasks

User interface changes

N/A

API changes

N/A

Data model changes

N/A