fix updatePartnerProfileAction bug

Author: steven-tey

apps/web/lib/zod/schemas/partner-profile.ts

@@ -175,7 +175,7 @@ export const partnerProfileChangeHistoryLogSchema = z.array(
   z.union([
     z.object({
       field: z.literal("country"),
-      from: z.string(),
+      from: z.string().nullable(),
       to: z.string(),
       changedAt: z.coerce.date(),
     }),