Update smd_thumbnail

Author: philwareham

composer.json

@@ -6,7 +6,7 @@
     "ezyang/htmlpurifier": "4.10.0",
     "textpattern/lock": "4.7.3",
     "textpattern/installer": "1.0.10",
-    "bloke/smd_thumbnail": "0.4.0-beta",
+    "bloke/smd_thumbnail": "0.5.3",
     "cara-tm/pat_if_amp": "0.3.7",
     "rah/rah_comment_spam": "0.9.0"
   }