Issue:
Bug: [CHORE] extend Currency TYPE in DB with more variants



### Feature Description

Below currencies to be added to the Currency type in DB

AFN
BTN
CDF
ERN
IRR
ISK
KPW
SDG
SYP
TJS
TMT
ZMW
ZWL

### Possible Implementation

Add diesel migrations

### Have you spent some time checking if this feature request has been raised before?

- [X] I checked and didn't find a similar issue

### Have you read the Contributing Guidelines?

- [X] I have read the [Contributing Guidelines](https://github.com/juspay/hyperswitch/blob/main/docs/CONTRIBUTING.md)

### Are you willing to submit a PR?

Yes, I am willing to submit a PR!

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
This PR adds a diesel migration for including below variants in Currency ENUM in database

```AFN
BTN
CDF
ERN
IRR
ISK
KPW
SDG
SYP
TJS
TMT
ZMW
ZWL
```


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

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can focus on the implementation (unless it is an obvious bug or documentation fix
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## How did you test it?
Ran migrations locally.


## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:
Ran migrations locally.

Patch:
diff --git a/migrations/2025-01-03-084904_add_currencies/down.sql b/migrations/2025-01-03-084904_add_currencies/down.sql
new file mode 100644
index 00000000000..e0ac49d1ecf
--- /dev/null
+++ b/migrations/2025-01-03-084904_add_currencies/down.sql
@@ -0,0 +1 @@
+SELECT 1;
diff --git a/migrations/2025-01-03-084904_add_currencies/up.sql b/migrations/2025-01-03-084904_add_currencies/up.sql
new file mode 100644
index 00000000000..14167a32cfc
--- /dev/null
+++ b/migrations/2025-01-03-084904_add_currencies/up.sql
@@ -0,0 +1,18 @@
+DO $$
+  DECLARE currency TEXT;
+  BEGIN
+    FOR currency IN
+      SELECT
+        unnest(
+          ARRAY ['AFN', 'BTN', 'CDF', 'ERN', 'IRR', 'ISK', 'KPW', 'SDG', 'SYP', 'TJS', 'TMT', 'ZWL']
+        ) AS currency
+      LOOP
+        IF NOT EXISTS (
+            SELECT 1
+            FROM pg_enum
+            WHERE enumlabel = currency
+              AND enumtypid = (SELECT oid FROM pg_type WHERE typname = 'Currency')
+          ) THEN EXECUTE format('ALTER TYPE "Currency" ADD VALUE %L', currency);
+        END IF;
+      END LOOP;
+END $$;
\ No newline at end of file