CPlusPlus: Fix compile before Qt6.5

Amends 7475b07.

Change-Id: I59494fe485cdb40b3af089698edc895dc2dd4519
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/3rdparty/cplusplus/Lexer.cpp

@@ -843,7 +843,7 @@ bool Lexer::scanUntilRawStringLiteralEndPrecise()
     while (_yychar) {
         slidingWindow.append(_yychar);
         if (slidingWindow.size() > _expectedRawStringSuffix.size())
-            slidingWindow.removeFirst();
+            slidingWindow.remove(0, 1);
         if (slidingWindow == _expectedRawStringSuffix) {
             _expectedRawStringSuffix.clear();
             yyinp();