Merge branch 'shim-signing-list' into 'master'

Update the list of signing templates from the shim source package

See merge request ftp-team/dak!114

config/debian/external-signatures.conf

@@ -44,9 +44,9 @@ External-Signature-Requests {
     };
     shim {
       Packages {
-        "shim-amd64-signed-template";
-        "shim-arm64-signed-template";
-        "shim-i386-signed-template";
+        "shim-helpers-amd64-signed-template";
+        "shim-helpers-arm64-signed-template";
+        "shim-helpers-i386-signed-template";
       };
       Architectures {
         "amd64"; "arm64"; "i386";