fix(build): modernize package configuration, dependencies, and test setup for current toolchain compatibility

ts/smartsmtp.classes.smartsmtp.ts

@@ -40,9 +40,9 @@ export class Smartsmtp {
    * sends a SmartMail
    */
   public async sendSmartMail(
-    smartmailArg: plugins.smartmail.Smartmail<any>,
+    smartmailArg: plugins.smartmail.Smartmail<Record<string, unknown>>,
     toArg: string,
-    dataArg = {}
+    dataArg: Record<string, unknown> = {},
   ) {
     const message: plugins.nodemailer.SendMailOptions = {
       from: smartmailArg.options.from,
@@ -55,15 +55,12 @@ export class Smartsmtp {
 
     // lets add attachments from smartmailArg
     for (const attachment of smartmailArg.attachments) {
-      message.attachments.push({
+      message.attachments!.push({
         filename: attachment.parsedPath.base,
         content: attachment.contentBuffer,
       });
     }
 
-    const response = await this.nodemailerTransport.sendMail(message).catch((err) => {
-      console.log(err);
-    });
-    return response;
+    return this.nodemailerTransport.sendMail(message);
   }
 }