Contractions don't remove dots

```
tokenizer =PragmaticTokenizer::Tokenizer.new({
  language: :pl,
  numbers: :all,
  downcase: false,
  contractions: { "os" => "osiedle", "os." => "osiedle" },
  expand_contractions: true
})

puts tokenizer.tokenize("Na os.Piłsudskiego")
```

The proper tokenization should be 
- `["Na", "osiedle", "Piłsudskiego"]`
while tokenizer returns
- `["Na", "Osiedle", ".", "Piłsudskiego"]`