Remove issue 4848 from 2.13.6 release notes

This issue was fixed in 2.13.3 and already mentioned there. It was
incorrectly added in the 2.13.6 release notes.

Change-Id: I2284f2ab302bf452f3572e5bd3a13e9c9a03ad78
diff --git a/releases/2.13.md b/releases/2.13.md
index ff49384..3c99742 100644
--- a/releases/2.13.md
+++ b/releases/2.13.md
@@ -514,9 +514,6 @@
 * [Issue 5298](https://bugs.chromium.org/p/gerrit/issues/detail?id=5298):
 Fix history token in Groups screen's "Members" tab.
 
-* [Issue 4848](https://bugs.chromium.org/p/gerrit/issues/detail?id=4848):
-Upgrade postgresql JDBC driver to 9.4.1211.jre7 to fix memory leaks.
-
 * Fix garbled text with Unicode display names obtained from HTTP headers.
 
 * Make error message for rejecting Egit placeholder Change-Id consistent.