Auto merge of #5907 - roberts1000:fix-magic-comment-style-for-gemspec-template, r=colby-swandale
Auto merge of #5907 - roberts1000:fix-magic-comment-style-for-gemspec-template, r=colby-swandale

Add new line after newgem gemspec template

### What was the end-user problem that led to this PR?

When using `bundle gem` to create a new gem, the created gemspec file starts with

```
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
```

Rubocop recommends having a blank line after magic comments (like `# coding: utf-8`).

### What was your diagnosis of the problem?

The rubocop style guide recommends having a blank line after "magic comments" ([see link](https://github.com/bbatsov/ruby-style-guide#separate-magic-comments-from-code)).   The main bundler.gemspec follows this recommendation, but the .gemspec, that is created for new gems, does not.

### What is your fix for the problem, implemented in this PR?

Update the template file to have a blank line after the magic comment.

### Why did you choose this fix out of the possible options?

It's what rubocop wants.

bundler/bundler,dilumnavanjana/bundler,mvz/bundler,bundler/bundler,dilumnavanjana/bundler,mvz/bundler