Add Linktree to social module (#2399)

[ChrisJr404]

Summary

Closes #2399 ("Add Social: Linktree", filed by @TheTechromancer).

Adds a Linktree entry to bbot/modules/social.py's social_media_platforms table so the social module emits a SOCIAL event for linktr.ee/<username> URLs alongside the existing platforms.

\"linktree\": (r\"linktr\\.ee/([a-zA-Z0-9._]{3,30})\", False),

The pattern follows Linktree's own username constraints (3–30 chars of letters/digits/_/.).

Test

test_module_social.TestSocial:

• adds <a href=\"https://linktr.ee/blacklanternsecurity\"/> to the response fixture,
• bumps the SOCIAL event count from 4 → 5,
• asserts platform/profile/url for the new Linktree event.

$ pytest bbot/test/test_step_2/module_tests/test_module_social.py -v
TestSocial::test_module_run PASSED
1 passed in 10.45s

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91%. Comparing base (5be4993) to head (210b95e).

Additional details and impacted files

@@          Coverage Diff          @@
##             dev   #3072   +/-   ##
=====================================
- Coverage     91%     91%   -0%     
=====================================
  Files        437     437           
  Lines      37509   37510    +1     
=====================================
- Hits       33925   33923    -2     
- Misses      3584    3587    +3     

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