`make ci` failing due to `Credentials::default` implementation

[joaommartins]

Describe the bug make ci fails on master branch due to clippy error on Credentials::default implementation.

To Reproduce make ci

Expected behavior make ci passes without skipping clippy check, by implementing the std::default::Default trait instead of a member function as it is currently.

Environment

• Rust version: [e.g. 1.62]
• lib version [e.g. 0.34]

Additional context This is a simple issue to fix, but the std::default::Default trait default() return is different to the current Credentials::default. Changing the return type creates the need to update all the usage of Credentials::default, as well as all the documentation and examples.

[durch]

@joaommartins thanks for raising, fixed