Use RuboCop RSpec 2.26

This commit makes this repo to use RuboCop RSpec 2.26 and suppress the following new offenses:

```console
$ bundle exec rubocop
(snip)

spec/project_spec.rb:261:11: C: [Correctable] RSpec/ExampleWording:
Do not use the future tense when describing your tests.
      it 'will not have a directory' do
          ^^^^^^^^^^^^^^^^^^^^^^^^^
spec/rubocop/cop/performance/count_spec.rb:185:9: C: [Correctable] RSpec/ExampleWording:
Do not use the future tense when describing your tests.
    it 'will not raise an error for Bundler.setup' do
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
spec/rubocop/cop/performance/count_spec.rb:189:9: C: [Correctable] RSpec/ExampleWording:
Do not use the future tense when describing your tests.
    it 'will not raise an error for RakeTask.new' do
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```

Gemfile

@@ -10,7 +10,7 @@ gem 'bump', require: false
 gem 'rake'
 gem 'rspec'
 gem 'rubocop', github: 'rubocop/rubocop'
-gem 'rubocop-rspec', '~> 2.25.0'
+gem 'rubocop-rspec', '~> 2.26.0'
 gem 'simplecov'
 gem 'test-queue'
 gem 'yard', '~> 0.9'

spec/project_spec.rb

@@ -258,7 +258,7 @@
 
       dir = File.expand_path('../changelog', __dir__)
 
-      it 'will not have a directory' do
+      it 'does not have a directory' do
         expect(Dir["#{dir}/*"].none? { |path| File.directory?(path) }).to be(true)
       end
 

spec/rubocop/cop/performance/count_spec.rb

@@ -182,11 +182,11 @@ def count(&block)
   end
 
   context 'properly parses non related code' do
-    it 'will not raise an error for Bundler.setup' do
+    it 'does not raise an error for Bundler.setup' do
       expect { inspect_source('Bundler.setup(:default, :development)') }.not_to raise_error
     end
 
-    it 'will not raise an error for RakeTask.new' do
+    it 'does not raise an error for RakeTask.new' do
       expect { inspect_source('RakeTask.new(:spec)') }.not_to raise_error
     end
   end