scripts/installer.sh: Add Ubuntu Lunar Lobster 23.04.

pkgs.tailscale.com added support in January, need to
add it to the installer script.

Signed-off-by: Denton Gentry <dgentry@tailscale.com>

scripts/installer.sh

@@ -306,7 +306,8 @@ main() {
 			   [ "$VERSION" != "hirsute" ] && \
 			   [ "$VERSION" != "impish" ] && \
 			   [ "$VERSION" != "jammy" ] && \
-			   [ "$VERSION" != "kinetic" ]
+			   [ "$VERSION" != "kinetic" ] && \
+			   [ "$VERSION" != "lunar" ]
 			then
 				OS_UNSUPPORTED=1
 			fi