patch 8.2.4043: using int for second argument of ga_init2()

Problem:    Using int for second argument of ga_init2().
Solution:   Remove unnessary type cast (int) when using sizeof().
diff --git a/src/digraph.c b/src/digraph.c
index 4c45e08..f46e43f 100644
--- a/src/digraph.c
+++ b/src/digraph.c
@@ -2632,7 +2632,7 @@
     keymap_unload();
 
     curbuf->b_kmap_state = 0;
-    ga_init2(&curbuf->b_kmap_ga, (int)sizeof(kmap_T), 20);
+    ga_init2(&curbuf->b_kmap_ga, sizeof(kmap_T), 20);
 
     // Set 'cpoptions' to "C" to avoid line continuation.
     p_cpo = (char_u *)"C";