shim-signed 1.48 source package in Ubuntu

Changelog

shim-signed (1.48) impish; urgency=medium

  [ Dimitri John Ledkov ]
  * Ship externally signed shims in the source package, instead of
    detached signatures.

  [ Steve Langasek ]
  * Restore build-time 'cmp' check to assert that the output of sbattach
    matches the binary received from Microsoft.
  * Include external-$arch.p7c in the clean target.

  [ Julian Andres Klode ]
  * download-signed: Work around non-HTTP apt sources
  * Update to shim 15.4-0ubuntu5:
    - Stop addending vendor dbx to MokListXRT during MokListX mirroring. This
      is causing systems to run out of EFI storage space, or just hang up
      when trying to write it (LP: #1924605) (LP: #1928434)
    - Further relax the check for variable mirroring on non-secureboot systems
      avoiding boot failures on out of space conditons (pull request #372)
    - Don't unhook ExitBootServices() when EBS protection is disabled
      (LP: #1931136) (pull request #378)

 -- Julian Andres Klode <email address hidden>  Tue, 22 Jun 2021 12:19:31 +0200