Update to the latest breaking API changes in go-text

[andydotxyz]

As happens sometimes the repo had an API break and so people upgrading all their deps get compile errors.
This resolves this and will be picked to release branch as well.

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[coveralls]

coverage: 66.032% (+0.005%) from 66.027%
when pulling 7fb896c on andydotxyz:fix/gotextapichanges
into 119d2f8 on fyne-io:develop.

[Jacalz]

Gosh how I wish people would stop doing bad stuff :/

Anyway, nice change and hopefully no problems going forward then :)

[andydotxyz]

Gosh how I wish people would stop doing bad stuff :/

Anyway, nice change and hopefully no problems going forward then :)

Yeah. Though isn't that what we said last time?

I wonder if we should go ahead and fork so we can manage in the unfortunate situation there are ever future breaks?

[Jacalz]

It should definitely safer and especially from breaking changes in the renderer (given that it has a tagged release now) but people can always forcefully update dependencies.

But I really don't think we should fork anything just because the dependency is making breaking changes. We'd add extra work for ourselves without anything to gain. The ones updating our own dependencies to versions with breaking changes are the ones to blame here.