Add test dependencies to attempt to fix CI

See: gnome-build-meta#372

data/meson.build

@@ -27,6 +27,9 @@ if desktop_file_validate.found()
     desktop_file_validate,
     args: [
       desktop_file.full_path()
+    ],
+    depends: [
+      desktop_file
     ]
   )
 endif
@@ -58,7 +61,10 @@ if appstream_util.found()
     'validate-appdata', appstream_util,
     args: [
       'validate-relax', '--nonet', appdata_file.full_path()
-    ]
+    ],
+    depends: [
+      appdata_file
+    ],
   )
 endif