Some kind of overlay texts generate urls which cause `400 Bad Request`

Some kind of overlay texts generate urls which cause `400 Bad Request`

## Describe the bug in a sentence or two.

```ruby
require 'open-uri'

def foo(text)
url = Cloudinary::Utils.cloudinary_url('sample', transformation: [
{
overlay: {
font_size: 24,
font_family: 'Sawarabi%20Gothic',
text: text
},
}
])

URI.open(url)
end

foo('hello') # No problem
foo('hello🍺') # => 400 Bad Request (OpenURI::HTTPError)
```

## Issue Type (Can be multiple)
- [ ] Build - Cannot install or import the SDK
- [ ] Performance - Performance issues
- [x] Behaviour - Functions are not working as expected (such as generate URL)
- [x] Documentation - Inconsistency between the docs and behaviour
- [ ] Other (Specify)

## Operating System
- [ ] Linux
- [ ] Windows
- [ ] macOS
- [x] All

## Environment and Libraries (fill in the version numbers)

```
$ bundle info cloudinary
* cloudinary (1.21.0)
Summary: Client library for easily using the Cloudinary service
Homepage: http://cloudinary.com
Path: /Users/ttanimichi/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/cloudinary-1.21.0

$ ruby -v
ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [arm64-darwin21]

$ bin/rails -v
Rails 6.1.4.1
```