Update Docs, Travis, and Containers to Use Postgres 11 (#9232)

* Update Docs and Containers to Use Postgres 11<, Bump Travis to 10

* Update installation docs as well

Co-authored-by: rhymes <rhymes@hey.com>

.travis.yml

@@ -7,7 +7,7 @@ cache:
 rvm:
   - 2.7.1
 addons:
-  postgresql: '9.6'
+  postgresql: '10' # Travis does not work out of the box with Postgres 11 yet
   chrome: 'stable'
   artifacts:
     paths:

README.md

@@ -99,7 +99,7 @@ A more complete overview of our stack is available in
   the badge.
 - [Yarn](https://yarnpkg.com/) 1.x: please refer to their
   [installation guide](https://classic.yarnpkg.com/en/docs/install).
-- [PostgreSQL](https://www.postgresql.org/) 9.5 or higher.
+- [PostgreSQL](https://www.postgresql.org/) 11 or higher.
 - [ImageMagick](https://imagemagick.org/): please refer to ImageMagick's
   [installation instructions](https://imagemagick.org/script/download.php).
 - [Redis](https://redis.io/) 4 or higher.

container-compose.yml

@@ -112,7 +112,7 @@ services:
     command: ["bundle", "exec", "sidekiq","-c","2"]
 
   db:
-    image: postgres:9.6.15-alpine
+    image: postgres:11-alpine
     container_name: dev_postgresql
     environment:
       POSTGRES_USER: devto

docker-compose.yml

@@ -112,7 +112,7 @@ services:
     command: ["bundle", "exec", "sidekiq","-c","2"]
 
   db:
-    image: postgres:9.6.15-alpine
+    image: postgres:11-alpine
     container_name: dev_postgresql
     environment:
       POSTGRES_USER: devto

docs/installation/linux.md

@@ -36,7 +36,7 @@ There are two ways to install Yarn.
 
 ### PostgreSQL
 
-DEV requires PostgreSQL version 9.5 or higher.
+DEV requires PostgreSQL version 11 or higher.
 
 1. Run
    `sudo apt update && sudo apt install postgresql postgresql-contrib libpq-dev`.

docs/installation/mac.md

@@ -20,7 +20,7 @@ Please refer to their [installation guide](https://yarnpkg.com/en/docs/install).
 
 ### PostgreSQL
 
-DEV requires PostgreSQL version 9.5 or higher.
+DEV requires PostgreSQL version 11 or higher.
 
 The easiest way to get started is to use
 [Postgres.app](https://postgresapp.com/). Alternatively, check out the official

docs/installation/windows.md

@@ -108,7 +108,7 @@ work fully. We install Node.js later on in the installation process.
 
 ### PostgreSQL
 
-DEV requires PostgreSQL version 9.5 or higher.
+DEV requires PostgreSQL version 11 or higher.
 
 If you don't have PostgreSQL installed on your Windows system, you can do so
 right now. WSL is able to connect to a PostgreSQL instance on your Windows