Add dev-qt from an older version of the gentoo repo

Qt5 has been removed, we restore it since we still use it.

dev-qt/qtserialport/qtserialport-6.12.9999.ebuild

@@ -0,0 +1,18 @@
+# Copyright 2021-2026 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit qt6-build
+
+DESCRIPTION="Serial port abstraction library for the Qt6 framework"
+
+if [[ ${QT6_BUILD_TYPE} == release ]]; then
+	KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~loong ~ppc ~ppc64 ~riscv ~x86"
+fi
+
+RDEPEND="
+	~dev-qt/qtbase-${PV}:6
+	virtual/libudev:=
+"
+DEPEND="${RDEPEND}"