Remove manual test that has been automated.

wiki/src/contribute/release_process/test.mdwn

@@ -571,9 +571,6 @@ language. You *really* have to reboot between each language.
   start without errors), and that `/var/log/syslog` seems OK.
 * MAT should be able to clean a PDF file, such as:
   <http://examples.itextpdf.com/results/part3/chapter12/pdf_metadata.pdf>
-* The Tails signing key shipped should be up-to-date (that is, neither it nor
-  one its subkeys must have expired, or be about to expire any time soon).
-  - `gpg --list-keys --with-colons 1202821CBE2CD9C1`
 * The "Report an error" desktop launcher should open the [[support]]
   page, both in English and in one language to which the website is
   translated (automate: [[!tails_ticket 6904]]).