patch 8.2.3296: Vim9: cannot add a number to a float

Problem:    Vim9: cannot add a number to a float.
Solution:   Accept a number if the destination is a float. (closes #8703)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 1c6e328..d2a6f68 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -7021,8 +7021,10 @@
 
 		    // Special case: assigning to @# can use a number or a
 		    // string.
-		    if (lhs_type == &t_number_or_string
-					    && rhs_type->tt_type == VAR_NUMBER)
+		    // Also: can assign a number to a float.
+		    if ((lhs_type == &t_number_or_string
+				|| lhs_type == &t_float)
+			    && rhs_type->tt_type == VAR_NUMBER)
 			lhs_type = &t_number;
 		    if (*p != '=' && need_type(rhs_type, lhs_type,
 					    -1, 0, cctx, FALSE, FALSE) == FAIL)