fix RDS version

Author: michaelwittig

chapter12/template.yaml

@@ -187,7 +187,7 @@ Resources:
       DBInstanceClass: 'db.t2.micro'
       DBName: discourse
       Engine: postgres
-      EngineVersion: '9.5.6'
+      EngineVersion: '9.6.22'
       MasterUsername: discourse
       MasterUserPassword: discourse
       VPCSecurityGroups:
@@ -249,7 +249,7 @@ Resources:
 
             # install packages
             yum -y group install "Development Tools"
-            yum -y install git zlib-devel postgresql95-devel libyaml-devel ImageMagick ruby23-devel nginx
+            yum -y install git zlib-devel postgresql96-devel libyaml-devel ImageMagick ruby23-devel nginx
             yum -y install --enablerepo=epel optipng jhead jpegoptim gifsicle libjpeg-turbo-utils
             update-alternatives --set ruby /usr/bin/ruby2.3
             gem install bundler -v "< 2.0, >= 1.3.0" --no-ri --no-rdoc