patch 8.2.1375: Vim9: method name with digit not accepted

Problem:    Vim9: method name with digit not accepted.
Solution:   Use eval_isnamec() instead of eval_isnamec1(). (closes #6613)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index e87634b..b3cca58 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3854,7 +3854,7 @@
 		}
 		if (ASCII_ISALPHA(*p) && p[1] == ':')
 		    p += 2;
-		for ( ; eval_isnamec1(*p); ++p)
+		for ( ; eval_isnamec(*p); ++p)
 		    ;
 		if (*p != '(')
 		{