Fix false-positive assert in panic

[iobtl]

This PR fixes a false-positive in clippy::panic when using the assert macro with its optional message parameter.

Fixes: #7433

changelog: panic_unimplemented.rs: added condition to exclude assert macro, similar to debug_assert
changelog: panicking_macros.rs: relevant tests to check for assert usage.

[flip1995]

@bors r+

Thanks!

[bors]

📌 Commit eeefbb7 has been approved by flip1995

[bors]

⌛ Testing commit eeefbb7 with merge 28e7699...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing 28e7699 to master...