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)

src/testdir/test_vim9_expr.vim

@@ -1674,14 +1674,14 @@ def Echo(arg: any): string
   return arg
 enddef
 
-def s:EchoArg(arg: any): string
+def s:Echo4Arg(arg: any): string
   return arg
 enddef
 
 def Test_expr7_call()
   assert_equal('yes', 'yes'->Echo())
   assert_equal('yes', 'yes'
-  			->s:EchoArg())
+  			->s:Echo4Arg())
   assert_equal(1, !range(5)->empty())
   assert_equal([0, 1, 2], --3->range())
 

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1375,
 /**/
     1374,
 /**/

src/vim9compile.c

@@ -3854,7 +3854,7 @@ compile_subscript(
 		}
 		if (ASCII_ISALPHA(*p) && p[1] == ':')
 		    p += 2;
-		for ( ; eval_isnamec1(*p); ++p)
+		for ( ; eval_isnamec(*p); ++p)
 		    ;
 		if (*p != '(')
 		{