Add gnupg to build-time test dependencies (and ostree-tests dependencies) as it is no longer transitively build-essential

debian/control

@@ -20,6 +20,7 @@ Build-Depends:
  e2fslibs-dev,
  elfutils,
  fuse,
+ gnupg <!nocheck>,
  gobject-introspection,
  gtk-doc-tools <!nodoc>,
  libarchive-dev,
@@ -154,6 +155,7 @@ Depends:
  fuse,
  gir1.2-ostree-1.0,
  gjs [!sparc64],
+ gnupg,
  ostree,
  python3,
  python3-yaml,