fix: fix config name from MARKETING_BASE_URL to MARKETING_SITE_BASE_URL

[asadali145]

Description:
The config name for the marketing URL is MARKETING_SITE_BASE_URL but MARKETING_BASE_URL is used in the Footer and it is not getting picked up from the config. This PR just fixes the name of the config variable.

[openedx-webhooks]

Thanks for the pull request, @asadali145! Please note that it may take us up to several weeks or months to complete a review and merge your PR.

Feel free to add as much of the following information to the ticket as you can:

• supporting documentation
• Open edX discussion forum threads
• timeline information ("this must be merged by XX date", and why that is)
• partner information ("this is a course on edx.org")
• any other information that can help Product understand the context for the PR

All technical communication about the code itself will be done via the GitHub pull request interface. As a reminder, our process documentation is here.

Please let us know once your PR is ready for our review and all tests are green.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ed5aeb8) 89.09% compared to head (a5ca665) 89.09%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #381   +/-   ##
=======================================
  Coverage   89.09%   89.09%           
=======================================
  Files           6        6           
  Lines          55       55           
  Branches       18       18           
=======================================
  Hits           49       49           
  Misses          6        6           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[openedx-webhooks]

@asadali145 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.