Add cron job to periodically purge

[glass-ships]

Short description of the changes:

Add a monthly cron job to purge expired data

Long description of the changes:

• Adds script which runs purge_expired_data command
• Adds a cron job to run this script at 00:00 on the 1st of each month
  • writes output to /var/log/cron.log
• Rename "deploy-config" to simply "deploy"
• Move django app docker files into this folder
• Add default auto field type to ensure longevity and suppress warnings
• Add counter to track how many runs are deleted

Check list for the pull request

• I have read the [CONTRIBUTING]
• I have read the [CODE_OF_CONDUCT]
• I have added tests for my changes
• I have updated the documentation accordingly

Check list for the reviewer

• I have read the [CONTRIBUTING]
• I have verified the proposed changes
• best software practices
  • all internal functions have an underbar, as is python standard
  • clearly named variables (better to be verbose in variable names)
  • code comments explaining the intent of code blocks
• All the tests are passing
• The documentation is up to date
• code comments added when explaining intent

Manual test for the reviewer

References

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.00%. Comparing base (7a4d038) to head (d7f665e).
Report is 4 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next      #31      +/-   ##
==========================================
+ Coverage   86.75%   90.00%   +3.24%     
==========================================
  Files          12       10       -2     
  Lines         317      310       -7     
==========================================
+ Hits          275      279       +4     
+ Misses         42       31      -11     

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[glass-ships]

codecov patch only failing because we don't have tests for migrations. (should we?)

[backmari]

Looks great 👌
We should test the migration in the test env to make sure that the app works as before after the changed primary key field type.

[backmari]

Maybe we can configure the code coverage to exclude migrations in the future

[glass-ships]

Maybe we can configure the code coverage to exclude migrations in the future

oh that's a good idea, I'll look at how to exclude folders!

[backmari]

Nice! Now the PR instead increases the code coverage 😁