patch 8.2.2859: Tcl test fails because of changed error message

Problem:    Tcl test fails because of changed error message.
Solution:   Adjust the expected error message.
diff --git a/src/testdir/test_tcl.vim b/src/testdir/test_tcl.vim
index b851ce8..a4554bb 100644
--- a/src/testdir/test_tcl.vim
+++ b/src/testdir/test_tcl.vim
@@ -145,7 +145,7 @@
 
   call assert_fails('tcl ::vim::expr x y',
         \           'wrong # args: should be "::vim::expr vimExpr"')
-  call assert_fails('tcl ::vim::expr 1-', 'E15: Invalid expression: 1-')
+  call assert_fails('tcl ::vim::expr 1-', 'E15: Invalid expression: "1-"')
 endfunc
 
 " Test ::vim::command