[Fix] stdc1 weight download link

[BeaverCC]

Motivation

Fix the weight download link in readme for stdc

Modification

Changed the download url

[CLAassistant]

All committers have signed the CLA.

[MengzhangLI]

Hi, thanks for your contribution.

Please fix the lint error.

[codecov]

Codecov Report

Merging #1206 (7ff03a4) into master (81b51ad) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1206   +/-   ##
=======================================
  Coverage   90.10%   90.10%           
=======================================
  Files         126      126           
  Lines        7430     7430           
  Branches     1239     1239           
=======================================
  Hits         6695     6695           
  Misses        530      530           
  Partials      205      205           

Flag	Coverage Δ
unittests	90.10% <ø> (ø)

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[OpenMMLab-Assistant003]

Hi @BeaverCC！First of all, we want to express our gratitude for your significant PR in the MMSegmentation project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

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Thank you again for your contribution❤ @BeaverCC