patch 8.2.4241: some type casts are redundant

Problem:    Some type casts are redundant.
Solution:   Remove the type casts. (closes #9643)
diff --git a/src/json.c b/src/json.c
index e19bc97..942d131 100644
--- a/src/json.c
+++ b/src/json.c
@@ -244,7 +244,7 @@
 		    if (i > 0)
 			ga_concat(gap, (char_u *)",");
 		    vim_snprintf((char *)numbuf, NUMBUFLEN, "%d",
-			    (int)blob_get(b, i));
+			    blob_get(b, i));
 		    ga_concat(gap, numbuf);
 		}
 		ga_append(gap, ']');