Remove unnecessary cast-to-int for parameter to QBitArray

It was ported to qsizetype after the cast was introduced

Change-Id: I00caff1d960f403990f93fcec6a7969e62b4cc99
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/testlib/qtest.h

@@ -105,7 +105,7 @@ template<> inline char *toString(const QBitArray &ba)
     qsizetype size = ba.size();
     char *str = new char[size + 1];
     for (qsizetype i = 0; i < size; ++i)
-        str[i] = "01"[ba.testBit(int(i))];
+        str[i] = "01"[ba.testBit(i)];
     str[size] = '\0';
     return str;
 }