Fix #1780: Add django-filter to INSTALLED_APPS

[seav]

Proposed changes in this pull request

• Fix Broken browsable API for any filterable view #1780:
  • According to this GitHub issue, we now need to include django-filter into our INSTALLED_APPS setting. I've checked that this fix works in the dev VM. Without it, we get the 500 error, and with it, filterable browsable API views work.

When should this PR be merged

When convenient.

Risks

None foreseen.

Follow-up actions

None.

Checklist (for reviewing)

General

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Functionality

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Code

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Tests

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Security

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Documentation

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