fix: Make public stripe key configurable

client/src/components/Donation/Donation.js

@@ -1,3 +1,4 @@
+/* global STRIPE_PUBLIC_KEY */
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
 import { bindActionCreators } from 'redux';
@@ -38,7 +39,7 @@ const propTypes = {
   show: PropTypes.bool
 };
 
-const stripeKey = 'pk_live_E6Z6xPM8pEsJziHW905zpAvF';
+const stripeKey = STRIPE_PUBLIC_KEY;
 
 class DonationModal extends Component {
   constructor(...props) {