Update the version numbers in README.version

Test: n/a
Change-Id: I7a3e32ddb8bb98b56ac4e420289d030fbd503533
diff --git a/README.version b/README.version
index 70eadc7..938a0ec 100644
--- a/README.version
+++ b/README.version
@@ -1,3 +1,3 @@
 URL: https://github.com/unicode-org/icu
-Version: 70.1
+Version: 71.1
 BugComponent: 23970