Update compiletest_rs dependency
Hello. I am trying to [update some Clippy dependencies](https://github.com/rust-lang/rust/pull/88517) in the rust repo. To help keep the overall number of dependencies down, I was asked to submit a PR here to update `compiletest_rs` to from `0.6.0` to `0.7.0`. I ran CI on my fork and the update didn't seem to cause any problems.