Bump rubocop-rspec from 2.5.0 to 2.6.0 (#15305)

Bumps [rubocop-rspec](https://github.com/rubocop/rubocop-rspec) from 2.5.0 to 2.6.0.
- [Release notes](https://github.com/rubocop/rubocop-rspec/releases)
- [Changelog](https://github.com/rubocop/rubocop-rspec/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop-rspec/compare/v2.5.0...v2.6.0)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile

@@ -150,7 +150,7 @@ group :development, :test do
   gem "rubocop", "~> 1.22", require: false # Automatic Ruby code style checking tool
   gem "rubocop-performance", "~> 1.12", require: false # A collection of RuboCop cops to check for performance optimizations in Ruby code
   gem "rubocop-rails", "~> 2.12", require: false # Automatic Rails code style checking tool
-  gem "rubocop-rspec", "~> 2.5", require: false # Code style checking for RSpec files
+  gem "rubocop-rspec", "~> 2.6", require: false # Code style checking for RSpec files
   gem "sassc-rails", "~> 2.1.2" # Integrate SassC-Ruby into Rails
   gem "spring", "~> 3.0" # Preloads your application so things like console, rake and tests run faster
   gem "spring-commands-rspec", "~> 1.0" # rspec command for spring

Gemfile.lock

@@ -699,7 +699,7 @@ GEM
       rubocop-ast (>= 1.12.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.12.0)
+    rubocop-ast (1.13.0)
       parser (>= 3.0.1.1)
     rubocop-performance (1.12.0)
       rubocop (>= 1.7.0, < 2.0)
@@ -708,7 +708,7 @@ GEM
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)
-    rubocop-rspec (2.5.0)
+    rubocop-rspec (2.6.0)
       rubocop (~> 1.19)
     ruby-next-core (0.12.0)
     ruby-prof (1.4.3)
@@ -1007,7 +1007,7 @@ DEPENDENCIES
   rubocop (~> 1.22)
   rubocop-performance (~> 1.12)
   rubocop-rails (~> 2.12)
-  rubocop-rspec (~> 2.5)
+  rubocop-rspec (~> 2.6)
   ruby-prof (~> 1.4)
   rubyzip (~> 2.3)
   s3_direct_upload (~> 0.1)