message: use application/json accept header when talking to relay server
diff: @@ -76,6 +76,7 @@ export async function gasEstimate(
  method: 'POST',
  headers: {
  'Content-Type': 'application/json', //eslint-disable-line @typescript-eslint/naming-convention
  + Accept: 'application/json', // eslint-disable-line @typescript-eslint/naming-convention
  },
  body: JSON.stringify({
  to,
  @@ -106,6 +107,7 @@ export async function getSendPayload(
  method: 'POST',
  headers: {
  'Content-Type': 'application/json', // eslint-disable-line @typescript-eslint/naming-convention
  + Accept: 'application/json', // eslint-disable-line @typescript-eslint/naming-convention
  },
  body: JSON.stringify({
  payment: spendAmount,
  @@ -142,6 +144,7 @@ export async function executeTransaction(
  method: 'POST',
  headers: {
  'Content-Type': 'application/json', //eslint-disable-line @typescript-eslint/naming-convention
  + Accept: 'application/json', // eslint-disable-line @typescript-eslint/naming-convention
  },
  body: JSON.stringify({
  to,
  @@ -181,6 +184,7 @@ export async function executeSend(
  method: 'POST',
  headers: {
  'Content-Type': 'application/json', //eslint-disable-line @typescript-eslint/naming-convention
  + Accept: 'application/json', // eslint-disable-line @typescript-eslint/naming-convention
  },
  body: JSON.stringify({
  nonce,
  