Update languagePt-BR

[menestrel-mkmb]

I was trying the app, and realize that the translation was for an old version, and it's not complete anymore, so I updated the language file.

For the language itself, a lot of text was splitted with "some" + "text", I was thinking about some linter, but on the "new" part I didn't see any of that, so I just got the rule of thumb: don't change unless test it, but...
I'm having an issue with signing keys, and after some gradle dep ('AudioTagger.updateMediaStore' and others), so I can't build the full project. I just PR this because you describe on the README:

Where for your new Language you have to add a new LanguageData(flag, name, languageCode) into the _supportedLanguages list, then, a new switch case in _loadLocale() function with your languageCode and return your new language File, open a Pull Request and after checking I will merge it!.

If you don't feel like doing this last step, you can still send me your new Language File via PullRequest and I will do it.

As you welcome just plain language files and do the configuration for yourself, I think that's OK to request this PR.

If you really want me to test it despise the README content, has been more than 2 years that I don't use Android Studio and code Flutter, so on my timeboxing for today I couldn't run the build to test, if someone could help me to realize how I can start from 'nothing installed' to AVD test, I can do that.