bpo-25324: add missing comma in Parser/tokenizer.c (GH-1910)

diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 7f2f3e6..51f98e9 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -108,7 +108,7 @@
     "<ERRORTOKEN>",
     "COMMENT",
     "NL",
-    "ENCODING"
+    "ENCODING",
     "<N_TOKENS>"
 };