title: Invalid Signature for MySQL repository
body: <p>I really hope you can help me as i've tried to find a solution myself for like 3 hours or so.
  I basically went through every stackoverflow post there was regarding this.</p>
  <p>What i'm trying to do is i want to <code>apt-get update</code> on my Debian Linux 10 environment.</p>
  <p>Every time i try to run this this comes up:</p>
  <pre><code>Get:1 http://repo.mysql.com/apt stable InRelease [3,566 B]
  Get:2 https://packages.sury.org/php buster InRelease [6,771 B]
  Err:1 http://repo.mysql.com/apt stable InRelease
    The following signatures were invalid: A4A9406876FCBD3C456770C88C718D3B5072E1F5
  Get:3 https://packages.sury.org/php buster/main i386 Packages [282 kB]
  Reading package lists... Done
  W: GPG error: http://repo.mysql.com/apt stable InRelease: The following signatures were invalid: 
  A4A9406876FCBD3C456770C88C718D3B5072E1F5
  E: The repository 'http://repo.mysql.com/apt stable InRelease' is not signed.
  N: Updating from such a repository can't be done securely, and is therefore disabled by default.
  N: See apt-secure(8) manpage for repository creation and user configuration details.
  </code></pre>
  <p>I have tried everything i found on stackoverflow and on the MySQL forum.
  I really hope you can help me.</p>
  <p>Thanks in advance.</p>