Upgrade Gerrit to 2.12.9

Change-Id: I81d2343e1aa3e54f40a37e7a108917e00bde1a5c
diff --git a/README.md b/README.md
index 5a71701..fd5309a 100644
--- a/README.md
+++ b/README.md
@@ -40,7 +40,10 @@
 
 ### Download the plugin
 
-Download [gerrit-saml-plugin](https://bintray.com/artifact/download/thesamet/maven/gerrit-saml-plugin-2.11.5-1.jar) and put it in $gerrit_site/lib/.
+Download Gerrit SAML plugin for the appropriate version of gerrit:
+
+- [gerrit-saml-plugin-2.12-1.jar](https://bintray.com/artifact/download/thesamet/maven/gerrit-saml-plugin-2.12-1.jar) and put it in $gerrit_site/lib/.
+- [gerrit-saml-plugin-2.11.5-1.jar](https://bintray.com/artifact/download/thesamet/maven/gerrit-saml-plugin-2.11.5-1.jar) and put it in $gerrit_site/lib/.
 
 ### Configure Gerrit to use the SAML filter:
 In `$site_path/etc/gerrit.config` file, the `[httpd]` section should contain
diff --git a/build.sbt b/build.sbt
index e55957c..f008805 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,6 +1,6 @@
 name := "gerrit-saml-plugin"
 
-val GerritVersion = "2.11.5"
+val GerritVersion = "2.12.9"
 
 version := GerritVersion + "-1"