chore: use HTTPS package metadata URLs

[youkiey]

Summary

• update the package homepage URL from plain HTTP to HTTPS
• update the package repository URL from the legacy unauthenticated git protocol to git+https

Validation

• node -e "const p=require('./package.json'); if(p.homepage!=='https://github.com/intercom/passport-intercom') throw new Error(p.homepage); if(p.repository.url!=='git+https://github.com/intercom/passport-intercom.git') throw new Error(p.repository.url); console.log(p.name, p.version, p.homepage, p.repository.url)"
• git diff --check
• npm pack --dry-run --ignore-scripts --json
• git ls-remote https://github.com/intercom/passport-intercom.git HEAD