fix: architecture selection in layer dispatch workflow

[gkkachi]

Previously, the workflow was downloading ARM64 binaries instead of x86_64, as reported in issue #72. This change updates the regex pattern to specifically select the x64.zip file from the GitHub release assets, ensuring the correct architecture is used for the Lambda layer.

$ JSON_RESPONSE=$(curl -s https://api.github.com/repos/Sparticuz/chromium/releases/latest)

# Previous
$  echo $JSON_RESPONSE | grep -Po '"browser_download_url": "\K[^"]+' 
https://github.com/Sparticuz/chromium/releases/download/v141.0.0/chromium-v141.0.0-layer.arm64.zip
https://github.com/Sparticuz/chromium/releases/download/v141.0.0/chromium-v141.0.0-layer.x64.zip
https://github.com/Sparticuz/chromium/releases/download/v141.0.0/chromium-v141.0.0-pack.arm64.tar
https://github.com/Sparticuz/chromium/releases/download/v141.0.0/chromium-v141.0.0-pack.x64.tar

# FIxed
$  echo $JSON_RESPONSE | grep -Po '"browser_download_url": "\K[^"]+x64\.zip'
https://github.com/Sparticuz/chromium/releases/download/v141.0.0/chromium-v141.0.0-layer.x64.zip

[iwaduarte]

Hi @gkkachi I am implementing a PR that will cater for both architectures. I am also fixing the outdated README.md and everything else related.

[gkkachi]

Hi @iwaduarte ,
Closing this PR in favor of PR #76, which presents a better approach. Thanks!