Use high-res PostGuard logo with text in email template

Replace the low-resolution (39x46px) logo-only image with the full
PostGuard logo including text, backed by a 600x326px PNG for crisp
rendering on retina displays.

Author: rubenhensen

templates/email/email.html

@@ -9,7 +9,7 @@
     <div style="background:#F2F8FD;background-color:#F2F8FD;padding:1em;">
         <div style="background:#F2F8FD;width:100%;max-width:600px;margin-left:auto;margin-right:auto;text-align:center;">
             <div style="margin:50px 0 20px 0">
-                <img src="https://postguard.eu/pg_logo_no_text.png" alt="PostGuard" width="82" height="82" style="display:block;margin:0 auto;" />
+                <img src="https://postguard.eu/pg_logo.png" alt="PostGuard" width="200" height="109" style="display:block;margin:0 auto;" />
             </div>
             <div style="background:#FFFFFF;padding:60px 50px;border-radius:8px;text-align:center;">
                 <p style="font-size:22px;font-weight:700;color:#030E17;margin:0 0 5px 0;line-height:30px;">