Added explicit "text" parameter in sendEmail call

refs https://github.com/TryGhost/Toolbox/issues/292

- This is groundwork before adding separate html/text generation. Should make future additions more readable

ghost/api-version-compatibility-service/lib/api-version-compatibility-service.js

@@ -2,7 +2,7 @@ class APIVersionCompatibilityService {
     /**
      *
      * @param {Object} options
-     * @param {Function} options.sendEmail - email sending function
+     * @param {(Object: {subject: String, to: String, text: String, html: String}) => Promise<any>} options.sendEmail - email sending function
      * @param {() => Promise<any>} options.fetchEmailsToNotify - email address to receive notifications
      * @param {(acceptVersion: String) => Promise<any>} options.fetchHandled - retrives already handled compatibility notifications
      * @param {(acceptVersion: String) => Promise<any>} options.saveHandled - persists already handled compatibility notifications
@@ -17,17 +17,19 @@ class APIVersionCompatibilityService {
     async handleMismatch({acceptVersion, contentVersion, userAgent = ''}) {
         if (!await this.fetchHandled(acceptVersion)) {
             const trimmedUseAgent = userAgent.split('/')[0];
-            const emailTemplate = `
+            const htmlContent = `
                 ${trimmedUseAgent} integration expected Ghost version: ${acceptVersion}
                 Current Ghost version: ${contentVersion}
             `;
+            const textContent = htmlContent;
 
             const emails = await this.fetchEmailsToNotify();
             for (const email of emails) {
                 await this.sendEmail({
                     subject: `Attention required: Your ${trimmedUseAgent} integration has failed`,
                     to: email,
-                    html: emailTemplate
+                    html: htmlContent,
+                    text: textContent
                 });
             }