Add Mozilla Firefox user agent to import script

[christianlupus]

Topic and Scope

This should help to make the import more stable.

Concerns/issues

We need to check if this solution helps and keep the sent FF version somewhat up to date.

Formal requirements

There are some formal requirements that should be satisfied. Please mark those by checking the corresponding box.

• I did check that the app can still be opened and does not throw any browser logs
• I created tests for newly added PHP code (check this if no PHP changes were made)
• I updated the OpenAPI specs and added an entry to the API changelog (check if API was not modified)
• I notified the matrix channel if I introduced an API change

[christianlupus]

/approve

[nextcloud-cookbook-bot]

Automatically approved by GitHub action on behalf of /approve

[github-actions]

Test Results

   12 files    584 suites   1m 37s ⏱️
  575 tests   575 ✅ 0 💤 0 ❌
2 300 runs  2 299 ✅ 1 💤 0 ❌

Results for commit ad9ae3d.