[cluster-test] Fix changelog generation
[cluster-test] Fix changelog generation

Github requires user agent per https://developer.github.com/v3/#user-agent-required

Closes: #2234
Approved by: phoenix-antigravity

aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core