Issue:
[FIX] add a configuration validation for workers

We don't have a validation check 
[number of workers in our config](https://github.com/juspay/hyperswitch/blob/94cd7b689758a71e13a3eaa655335e658d13afc8/crates/router/src/configs/settings.rs#L422) . But if the number of workers is zero actix straight out panics. Ref: https://docs.rs/actix-web/latest/actix_web/struct.HttpServer.html#method.workers

Resolution:
<think>
PR Context:
- Title: fix(router): added validation check to number of workers in config
- Merged: 2024-02-07T09:33:32Z
- Files changed: 1 files
- Commits: 2 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Added validation check on number workers


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provid
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** fix(router): added validation check to number of workers in config (#3533)
Files to modify:


**crates/router/src/configs/validations.rs**
  Modify existing code