Reduce MatchPoints for U1.RUCK test

More and more submissions are coming in with bad values for this test,
likely due to VPNs or possibly checksum offload. Reducing the points
value improves accuracy of near-matches, as it is rarely anything but G
or 0.

nmap-os-db

@@ -41,7 +41,7 @@ T4(R=100%DF=20%T=15%TG=15%W=25%S=20%A=20%F=30%O=10%RD=20%Q=20)
 T5(R=100%DF=20%T=15%TG=15%W=25%S=20%A=20%F=30%O=10%RD=20%Q=20)
 T6(R=100%DF=20%T=15%TG=15%W=25%S=20%A=20%F=30%O=10%RD=20%Q=20)
 T7(R=80%DF=20%T=15%TG=15%W=25%S=20%A=20%F=30%O=10%RD=20%Q=20)
-U1(R=50%DF=20%T=15%TG=15%IPL=100%UN=100%RIPL=100%RID=100%RIPCK=100%RUCK=100%RUD=100)
+U1(R=50%DF=20%T=15%TG=15%IPL=100%UN=100%RIPL=100%RID=100%RIPCK=100%RUCK=50%RUD=100)
 IE(R=50%DFI=40%T=15%TG=15%CD=100)
 
 # 2N VOIP doorbell