Use foundry releases on external tests #16347
Description
The external test jobs have been consistently failing (for example, see: https://app.circleci.com/pipelines/github/argotorg/solidity/41064/workflows/804d4a9f-91fa-40e4-a2d1-8e6e997fd752/jobs/1914135 and https://app.circleci.com/jobs/github/argotorg/solidity/1911617). The errors are related to the install_foundry step, which attempts to download the latest nightly builds from Foundry on each run.
The job uses a GitHub token with read permissions to avoid hitting rate limits for unauthorized requests, but due to the frequency of the downloads, occasional failures still occur with 503 or 403.
This setup was initially implemented to test for breaking changes while Foundry did not have stable releases (only pre-releases). However, since Foundry now appears to have proper releases, we should modify the logic to use stable releases instead of nightly builds.