fix: give one native system id one slug

RetroDECK filed coco as tandy-coco and Dragon as dragon-32-64, MiSTer
filed COCO3 as tandy-coco and Recalbox kept its raw ids, so none of
them met xroar's coco, coco3 and dragon64 and its ROMs reached no
system. The scraper maps now agree and a test holds every shared
native id to one system.

scripts/scraper/recalbox_scraper.py

@@ -49,6 +49,8 @@ SOURCE_URL = (
 
 SYSTEM_SLUG_MAP = {
     "3do": "3do",
+    "dragon": "dragon64",
+    "trs80coco": "coco",
     "amiga600": "commodore-amiga",
     "amiga1200": "commodore-amiga",
     "amigacd32": "commodore-amiga",