bug: export::path:absolute function fails when TS_RS_EXPORT_DIR is set to an absolute path and the path_bug test is executed

[escritorio-gustavo]

Describe the bug
Certain combinations of absolute paths and ../. path components can trick the aboslute function into doing nothing

To Reproduce

1. Create a file in this repo at .cargo/config.toml with the following content:

[env]
TS_RS_EXPORT_DIR = { value = "./whatever", relative = true }

2. Run cargo test

Why is this happening?
The path ./whatever is automatically transformed into an absolute path by cargo due to the relative flag.
The path_bug test checks if exporting to ../somewhere/ works.
The paths are combined into something like /usr/me/../somewhere and passed into the absolute function.
The absolute function, seeing the path starts at the root directory / assumes this is already an absolute path and does nothing
The diff_paths function, not expecting the absolute function to return a path containing . or .., panics

Version
8.1.0