Bump pg from 1.3.3 to 1.3.4

Bumps [pg](https://github.com/ged/ruby-pg) from 1.3.3 to 1.3.4.
- [Release notes](https://github.com/ged/ruby-pg/releases)
- [Changelog](https://github.com/ged/ruby-pg/blob/master/History.rdoc)
- [Commits](https://github.com/ged/ruby-pg/compare/v1.3.3...v1.3.4)

---
updated-dependencies:
- dependency-name: pg
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile

@@ -34,7 +34,7 @@ gem 'therubyracer', group: :therubyracer
 # Use --without <group> argument to skip unnecessary drivers
 gem 'sqlite3', group: :sqlite
 gem 'mysql2', '~> 0.5.3', group: :mysql
-gem 'pg', '~> 1.3.3', group: :postgresql
+gem 'pg', '~> 1.3.4', group: :postgresql
 
 group :development do
   gem 'spring'