fix: ensure code is finished compiling before returning cached file

[jsakas]

Hi @mammadataei - earlier I opened #35

After reviewing the code, I think maybe the problem is that it is not waiting for Vite to finish bundling before returning the cache file location. The process probably works fine for simple files with no external imports. However, in my codebase, we often import files from src, for example utilities which slows down the Vite bundler and makes the file not immediately available.

In the documentation it notes only resolving the promise when the file is written to disk:

https://docs.cypress.io/api/plugins/preprocessors-api#The-callback-function-should-return-one-of-the-following

The callback function should return one of the following:

A promise* that eventually resolves the path to the built file**.
A promise* that eventually rejects with an error that occurred during processing.

• The promise should resolve only after the file has completed writing to disk. The promise resolving is a signal that the file is ready to be served to the browser.

[mammadataei]

Hi @jsakas. Thanks a lot for your contribution. Merged and released in v1.3.1.