Remove dark mode notices

[zackkrida]

Description

This PR removes the dark mode announcement notices from Openverse's homepage. The feature launched in December of 2024 and no longer needs to be framed as "new".

Testing Instructions

Checklist

• My pull request has a descriptive title (not a vague title likeUpdate index.md).
• My pull request targets the default branch of the repository (main) or a parent feature branch.
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added or updated tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no visible errors.
• I ran the DAG documentation generator (ov just catalog/generate-docs for catalog
  PRs) or the media properties generator (ov just catalog/generate-docs media-props
  for the catalog or ov just api/generate-docs for the API) where applicable.

Developer Certificate of Origin

Developer Certificate of Origin

Developer Certificate of Origin
Version 1.1

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Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
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    by me, under the same open source license (unless I am
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    in the file; or

(c) The contribution was provided directly to me by some other
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    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

[zackkrida]

Thanks for the review, @obulat! I've updated the PR with the requested cleanup.

[github-actions]

Latest k6 run output¹

     ✓ status was 200

     checks.........................: 100.00% ✓ 394      ✗ 0   
     data_received..................: 91 MB   378 kB/s
     data_sent......................: 52 kB   214 B/s
     http_req_blocked...............: avg=38.43µs  min=2.43µs   med=4.7µs    max=1.83ms   p(90)=149.57µs p(95)=178.06µs
     http_req_connecting............: avg=24.91µs  min=0s       med=0s       max=1.76ms   p(90)=99.83µs  p(95)=117.52µs
     http_req_duration..............: avg=154.49ms min=15.79ms  med=107.33ms max=933.58ms p(90)=347.99ms p(95)=412.01ms
       { expected_response:true }...: avg=154.49ms min=15.79ms  med=107.33ms max=933.58ms p(90)=347.99ms p(95)=412.01ms
   ✓ http_req_failed................: 0.00%   ✓ 0        ✗ 394 
     http_req_receiving.............: avg=165.56µs min=45.92µs  med=135.96µs max=5.24ms   p(90)=232.81µs p(95)=280.16µs
     http_req_sending...............: avg=25.87µs  min=6.84µs   med=23.58µs  max=125.75µs p(90)=39.56µs  p(95)=46.59µs 
     http_req_tls_handshaking.......: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=154.29ms min=15.7ms   med=107.2ms  max=933.25ms p(90)=347.74ms p(95)=411.81ms
     http_reqs......................: 394     1.638309/s
     iteration_duration.............: avg=829.13ms min=195.56ms med=893.12ms max=1.69s    p(90)=1.09s    p(95)=1.14s   
     iterations.....................: 74      0.307703/s
     vus............................: 0       min=0      max=6 
     vus_max........................: 60      min=60     max=60

Footnotes

1. This comment will automatically update with new output each time k6 runs for this PR ↩

[obulat]

Thank you, @zackkrida ❤️