Rename an incorrect unreleased entry filename

Follow #9167.

This PR adds the following project spec and
renames the incorrect unreleased entry filename of #9167.

```console
% bundle exec rspec spec/project_spec.rb:239

Randomized with seed 30085
.F

Failures:

  1) RuboCop Project Changelog future entries For
  /Users/koic/src/github.com/rubocop-hq/rubocop/spec/../changelog/
support_autocorrect_for_style_single_line_block_params.md
  starts with `new_`, `fix_`, or `change_`
     Failure/Error:
  expect(File.basename(path)).to(match(/\A(new|fix|change)_.+/))

       expected
       "support_autocorrect_for_style_single_line_block_params.md" to
       match /\A(new|fix|change)_.+/
       Diff:
       @@ -1 +1 @@
       -/\A(new|fix|change)_.+/
       +"support_autocorrect_for_style_single_line_block_params.md"

     # ./spec/project_spec.rb:240:in `block (6 levels) in
       <top (required)>'

Finished in 0.01424 seconds (files took 1.53 seconds to load)
2 examples, 1 failure

Failed examples:

rspec './spec/project_spec.rb[1:3:4:2:5]' # RuboCop Project Changelog
future entries For
/Users/koic/src/github.com/rubocop-hq/rubocop/spec/../changelog/
support_autocorrect_for_style_single_line_block_params.md
starts with `new_`, `fix_`, or `change_`
```

spec/project_spec.rb

@@ -235,6 +235,10 @@
           it 'has a link to the contributors at the end' do
             expect(entries).to all(match(/\(\[@\S+\]\[\](?:, \[@\S+\]\[\])*\)$/))
           end
+
+          it 'starts with `new_`, `fix_`, or `change_`' do
+            expect(File.basename(path)).to(match(/\A(new|fix|change)_.+/))
+          end
         end
       end
     end