Fix for Clippy `HSTRING` interior mutability warnings in nightly

[riverar]

Fixes: #3020.

Disables interior mutability lints on the HSTRING macro due to a false positive.

More information:

• https://rust-lang.github.io/rust-clippy/master/index.html#/declare_interior_mutable_const
• https://rust-lang.github.io/rust-clippy/master/index.html#/borrow_interior_mutable_const