Upgraded to Ruby 2.6.2 in more files

.ruby-version

@@ -1 +1 @@
-2.6.1
+2.6.2

.travis.yml

@@ -1,6 +1,6 @@
 language: ruby
 rvm:
-  - "2.6.1"
+  - "2.6.2"
 
 before_install:
   - "phantomjs --version"

Dockerfile

@@ -1,4 +1,4 @@
-FROM ruby:2.6.1
+FROM ruby:2.6.2
 RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
 RUN mkdir /myapp
 WORKDIR /myapp