Bump rspec-rails from 3.8.2 to 3.9.0 (mastodon#12241)

Bumps [rspec-rails](https://github.com/rspec/rspec-rails) from 3.8.2 to 3.9.0.
- [Release notes](https://github.com/rspec/rspec-rails/releases)
- [Changelog](https://github.com/rspec/rspec-rails/blob/master/Changelog.md)
- [Commits](rspec/rspec-rails@v3.8.2...v3.9.0)

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

Gemfile

@@ -106,7 +106,7 @@ group :development, :test do
   gem 'i18n-tasks', '~> 0.9', require: false
   gem 'pry-byebug', '~> 3.7'
   gem 'pry-rails', '~> 0.3'
-  gem 'rspec-rails', '~> 3.8'
+  gem 'rspec-rails', '~> 3.9'
 end
 
 group :production, :test do

Gemfile.lock

@@ -235,7 +235,7 @@ GEM
       multi_json
     encryptor (3.0.0)
     equatable (0.6.1)
-    erubi (1.8.0)
+    erubi (1.9.0)
     et-orbi (1.1.6)
       tzinfo
     excon (0.62.0)
@@ -488,8 +488,8 @@ GEM
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.2.0)
-      loofah (~> 2.2, >= 2.2.2)
+    rails-html-sanitizer (1.3.0)
+      loofah (~> 2.3)
     rails-i18n (5.1.3)
       i18n (>= 0.7, < 2)
       railties (>= 5.0, < 6)
@@ -537,26 +537,26 @@ GEM
     rpam2 (4.0.2)
     rqrcode (0.10.1)
       chunky_png (~> 1.0)
-    rspec-core (3.8.0)
-      rspec-support (~> 3.8.0)
-    rspec-expectations (3.8.2)
+    rspec-core (3.9.0)
+      rspec-support (~> 3.9.0)
+    rspec-expectations (3.9.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
-    rspec-mocks (3.8.0)
+      rspec-support (~> 3.9.0)
+    rspec-mocks (3.9.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
-    rspec-rails (3.8.2)
+      rspec-support (~> 3.9.0)
+    rspec-rails (3.9.0)
       actionpack (>= 3.0)
       activesupport (>= 3.0)
       railties (>= 3.0)
-      rspec-core (~> 3.8.0)
-      rspec-expectations (~> 3.8.0)
-      rspec-mocks (~> 3.8.0)
-      rspec-support (~> 3.8.0)
+      rspec-core (~> 3.9.0)
+      rspec-expectations (~> 3.9.0)
+      rspec-mocks (~> 3.9.0)
+      rspec-support (~> 3.9.0)
     rspec-sidekiq (3.0.3)
       rspec-core (~> 3.0, >= 3.0.0)
       sidekiq (>= 2.4.0)
-    rspec-support (3.8.0)
+    rspec-support (3.9.0)
     rubocop (0.75.1)
       jaro_winkler (~> 1.5.1)
       parallel (~> 1.10)
@@ -775,7 +775,7 @@ DEPENDENCIES
   redis-namespace (~> 1.5)
   redis-rails (~> 5.0)
   rqrcode (~> 0.10)
-  rspec-rails (~> 3.8)
+  rspec-rails (~> 3.9)
   rspec-sidekiq (~> 3.0)
   rubocop (~> 0.75)
   rubocop-rails (~> 2.3)