Asynchronous Handling Issue in API Key Hashing Middleware

[Jatin24062005]

Previously, next() was being called after hashing each API key, which caused multiple calls and issues. The new solution uses a pendingTasks counter to wait until all async operations are completed. This fix prevents Mongoose errors and premature next() calls, ensuring proper API key hashing.
The Code i have been manipulated works on the simple principle of critical section problem simmilar to peterson's solution.
These will fix the issue easily .

Fixes #issue-[3016](url)

Changes:

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123