ICU-20873 Add KEYS file to cpyskip.txt for Travis Linter.
diff --git a/.cpyskip.txt b/.cpyskip.txt
index fc8af8a..878546e 100644
--- a/.cpyskip.txt
+++ b/.cpyskip.txt
@@ -16,6 +16,8 @@
 .travis.yml
 .appveyor.yml
 .ci-builds/*
+# PGP Keys
+KEYS
 # suffix matches - start with '*'.  They are turned into as RE, '.brk$'
 *.brk
 *.bz2