gnu: gs-fonts: Add missing module imports.

Fixes <https://bugs.gnu.org/26805>.

* gnu/packages/ghostscript.scm (gs-fonts): Add missing modules to
%modify-phases call: gnu-build-system, utils, srfi-1.

Signed-off-by: Danny Milosavljevic <dannym@scratchpost.org>

gnu/packages/ghostscript.scm

@@ -273,6 +273,10 @@ architecture.")
    (build-system gnu-build-system)
    (arguments
     `(#:tests? #f ; nothing to check, just files to copy
+
+      #:modules ((guix build gnu-build-system)
+                 (guix build utils)
+                 (srfi srfi-1))
       #:phases
       (modify-phases %standard-phases
         (delete 'configure)