yaz: fix broken indirect linkage

This formula depends on `gnutls`, which currently depends on `guile`.
The `guile` dependency will be removed from `gnutls` in #122955, but
that will result in broken linkage for this formula.

We can fix that by declaring a dependency on the indirectly linked
formula.

The new dependency is already present in this formula's dependency tree,
so this change (by itself), should be a no-op.

Closes #123085.

Signed-off-by: BrewTestBot <1589480+BrewTestBot@users.noreply.github.com>

Formula/yaz.rb

@@ -37,6 +37,7 @@ class Yaz < Formula
   depends_on "pkg-config" => :build
   depends_on "gnutls"
   depends_on "icu4c"
+  depends_on "readline" # Possible opportunistic linkage. TODO: Check if this can be removed.
 
   uses_from_macos "libxml2"
   uses_from_macos "libxslt"