Updated MailChimp API key URLs to the new link (#7167)

# Description & Issue number it closes 
<!-- The old API key URLS had been updated to the new link based on the
link provided addressing the iuuse in issue #7156 . though I'm not sure
about what exactly to update the wiki from the context provided . And
Since the lack of clarity from the context , I had to leave it with no
changes from my side . However assumed the main part of the issue has
already been solved.-->

## Screenshots (if appropriate)
<!-- Before and after --> 

## How to test the changes?

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update

# How Has This Been Tested?

<!-- Please describe the tests that you ran to verify your changes.
Provide instructions so we can reproduce. Please also list any relevant
details for your test configuration -->

# Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules

src/ChurchCRM/dto/SystemConfig.php

@@ -239,7 +239,7 @@ private static function buildConfigs(): array
             'sConfirmSincerely'                    => new ConfigItem(1048, 'sConfirmSincerely', 'text', 'Sincerely', gettext('Used to end a letter before Signer')),
             'sDear'                                => new ConfigItem(1049, 'sDear', 'text', 'Dear', gettext('Text before name in emails/reports')),
             'sGoogleTrackingID'                    => new ConfigItem(1050, 'sGoogleTrackingID', 'text', '', gettext('Google Analytics Tracking Code')),
-            'sMailChimpApiKey'                     => new ConfigItem(2000, 'sMailChimpApiKey', 'text', '', '', 'http://kb.mailchimp.com/accounts/management/about-api-keys'),
+            'sMailChimpApiKey'                     => new ConfigItem(2000, 'sMailChimpApiKey', 'text', '', '', 'https://mailchimp.com/help/about-api-keys/'),
             'sDepositSlipType'                     => new ConfigItem(2001, 'sDepositSlipType', 'choice', 'QBDT', gettext('Deposit ticket type.  QBDT - Quickbooks'), '', '{"Choices":["QBDT"]}'),
             'bAllowEmptyLastName'                  => new ConfigItem(2010, 'bAllowEmptyLastName', 'boolean', '0', gettext('Set true to allow empty lastname in Person Editor.  Set false to validate last name and inherit from family when left empty.')),
             'iPersonNameStyle'                     => new ConfigItem(2020, 'iPersonNameStyle', 'choice', '4', '', '', json_encode(SystemConfig::getNameChoices(), JSON_THROW_ON_ERROR)),

src/mysql/upgrade/2.0.0.sql

@@ -15,7 +15,7 @@ VALUES
   (24, 'bEmailSend', '', 'boolean', '', 'If you wish to be able to send emails from within ChurchCRM. This requires\reither an SMTP server address to send from or sendmail installed in PHP.', 'General', NULL),
   (999, 'bRegistered', '0', 'boolean', '0',
    'ChurchCRM has been registered.  The ChurchCRM team uses registration information to track usage.  This information is kept confidential and never released or sold.  If this field is true the registration option in the admin menu changes to update registration.', 'General', NULL),
-  (2000, 'mailChimpApiKey', '', 'text', '', 'see http://kb.mailchimp.com/accounts/management/about-api-keys', 'General', NULL),
+  (2000, 'mailChimpApiKey', '', 'text', '', 'see https://mailchimp.com/help/about-api-keys/', 'General', NULL),
   (1034, 'sChurchChkAcctNum', '111111111', 'text', '', 'Church Checking Account Number', 'ChurchInfoReport', NULL);
 UPDATE user_usr
 SET usr_Style = "skin-blue";