chore(stellar-wallet-snap): migration phase C - add Stellar secret at CI

[stanleyyconsensys]

Explanation

This PR is to prepare the ENV var for the CI process

those ENV var already added into the repo

Migration process

• feat(stellar-wallet-snap): migration phase B - add snap source code into merged-packages #153
• chore(stellar-wallet-snap): migration phase B - update tsconfig + align dependencise + update readme #159
• chore(stellar-wallet-snap): migration phase C - add Stellar secret at CI #160
• Next chore(stellar-wallet-snap): migration phase C - Integration Stellar into packages + Linter and constraints fixes + update changelog  #161

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them