Code coverage is no longer accurate due to the introduction of Rust

[fpgmaas]

Now that we have added Rust to our projects, out code coverage is no longer accurately measured. Code coverage is only measured based on the python/deptry directory, but we should also include coverage on our .rs files in the src directory.

Currently, all our unit tests are in Python. We might also want to consider writing unit tests in Rust later, so we can test functions that are not exposed to Python. However, for this issue I propose we leave that out of scope.

Maybe we can take a look at rust-python-coverage, which uses cargo-llvm-cov