[explorer] - fix epochs count (#10799)

## Description 

Fixes the Epochs count in the epochs table footer

## Test Plan 

How did you test the new or updated feature?

---
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### Type of Change (Check all that apply)

- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

apps/explorer/src/pages/epochs/EpochsTable.tsx

@@ -30,7 +30,7 @@ export function EpochsTable({
         ['epochs', 'current'],
         async () => enhancedRpc.getCurrentEpoch(),
         {
-            select: (epoch) => epoch.epoch + 1,
+            select: (epoch) => Number(epoch.epoch) + 1,
         }
     );