Fix The River's Gift. to The River's Gift (#339)

Just did a simple find/replace which I think should work!

card_db_src/cz/cards_cz.json

@@ -540,7 +540,7 @@
     "The Forest's Gift": {},
     "The Moon's Gift": {},
     "The Mountain's Gift": {},
-    "The River's Gift.": {},
+    "The River's Gift": {},
     "The Sea's Gift": {},
     "The Sky's Gift": {},
     "The Sun's Gift": {},