chore(contact): use info@andreas-dahm.eu as contact email

The old private address is no longer used. Update the imprint
page, the mail button and the README.

src/app/shared/SharedFunctions.ts

@@ -2,8 +2,8 @@
 export class SharedFunctions {
   static openMail(event?: Event) {
     event?.preventDefault();
-    const user = 'andreas.dahm';
-    const domain = 'gmail.com';
+    const user = 'info';
+    const domain = 'andreas-dahm.eu';
     globalThis.location.href = `mailto:${user}@${domain}`;
   }