Update tests since ? macro op is supported on 2015.

src/test/ui/parser/macro/issue-33569.rs

@@ -1,7 +1,7 @@
 macro_rules! foo {
     { $+ } => { //~ ERROR expected identifier, found `+`
                 //~^ ERROR missing fragment specifier
-        $(x)(y) //~ ERROR expected `*` or `+`
+        $(x)(y) //~ ERROR expected one of: `*`, `+`, or `?`
     }
 }
 

src/test/ui/parser/macro/issue-33569.stderr

@@ -4,7 +4,7 @@ error: expected identifier, found `+`
 LL |     { $+ } => {
    |        ^
 
-error: expected `*` or `+`
+error: expected one of: `*`, `+`, or `?`
   --> $DIR/issue-33569.rs:4:13
    |
 LL |         $(x)(y)