[Issue 23626] [REG2.096] Template deduction with auto const ref Args... and delegate

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23626

--- Comment #1 from johanengelen at weka.io ---
This frontend change "fixes" the errors (3 lines removed):
diff dmd/mtype.d:
```
    /** Extends TypeNext.constConv by also checking for matching attributes **/
    override MATCH constConv(Type to)
    {
-        // Attributes need to match exactly, otherwise it's an implicit
conversion
-        if (this.ty != to.ty || !this.attributesEqual(cast(TypeFunction) to))
-            return MATCH.nomatch;
```

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