fix: 🐛 convert partyIdType to lowercase to avoid 404 from momo

Sending uppercase representation of partyIdType in disbursements
isPayerActive api returns 404 but works in transfer request body. Hence,
partyIdType is converted to lowercase before including in the uri

src/disbursements.ts

@@ -177,7 +177,7 @@ export default class Disbursements {
     type: PartyIdType = PartyIdType.MSISDN
   ): Promise<string> {
     return this.client
-      .get<string>(`/disbursement/v1_0/accountholder/${type}/${id}/active`)
+      .get<string>(`/disbursement/v1_0/accountholder/${String(type).toLowerCase()}/${id}/active`)
       .then(response => response.data);
   }
 }

test/disbursements.test.ts

@@ -151,7 +151,7 @@ describe("Disbursements", function() {
       ).to.be.fulfilled.then(() => {
         expect(mockAdapter.history.get).to.have.lengthOf(1);
         expect(mockAdapter.history.get[0].url).to.eq(
-          "/disbursement/v1_0/accountholder/MSISDN/0772000000/active"
+          "/disbursement/v1_0/accountholder/msisdn/0772000000/active"
         );
       });
     });

test/mock.ts

@@ -61,7 +61,7 @@ export function createMock(): [AxiosInstance, MockAdapter] {
 
   mock
     .onGet(
-      /\/disbursement\/v1_0\/accountholder\/(MSISDN|EMAIL|PARTY_CODE)\/\w+/
+      /\/disbursement\/v1_0\/accountholder\/(msisdn|email|party_code)\/\w+/
     )
     .reply(200, "true");