fix: Account.createTransfer return type

[Torres-ssf]

Summary

Use ScriptTransactionRequest instead of TransactionRequest as the returning type of the Account method createTransfer

Checklist

• All changes are covered by tests (or not applicable)
• All changes are documented (or not applicable)
• I reviewed the entire PR myself (preferably, on GH UI)
• I described all Breaking Changes (or there's none)

[github-actions]

Coverage Report:

Lines	Branches	Functions	Statements
79.33%(+0%)	71.57%(+0%)	77.55%(+0%)	79.48%(+0%)

Changed Files:

Coverage values did not change👌.