network: silence -Wimplicit-exception-spec-mismatch

`noexcept` drop implicit noexcept from QHttp2Connection dtor

Pick-to: 6.8 6.9
Change-Id: I0ff6afb1f70d3fe68739380b6f18c308871aa327
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/network/access/qhttp2connection.cpp

@@ -1029,7 +1029,7 @@ QHttp2Connection::QHttp2Connection(QIODevice *socket) : QObject(socket)
     // socket connections.
 }
 
-QHttp2Connection::~QHttp2Connection() noexcept
+QHttp2Connection::~QHttp2Connection()
 {
     // delete streams now so that any calls it might make back to this
     // Connection will operate on a valid object.