The `<scale>` argument of `guides()` cannot be `FALSE` deprecation

[artur-sannikov]

As of ggplot 3.3.4, I get this warning:

Warning: The `<scale>` argument of `guides()` cannot be `FALSE`. Use "none" instead as of ggplot2 3.3.4.
ℹ The deprecated feature was likely used in the MOFA2 package.
  Please report the issue at <https://github.com/bioFAM/MOFA2>.
This warning is displayed once every 8 hours.
Call `lifecycle::last_lifecycle_warnings()` to see where this warning was generated.

<warning/lifecycle_warning_deprecated>
Warning:
The `<scale>` argument of `guides()` cannot be `FALSE`. Use "none" instead as of ggplot2 3.3.4.
ℹ The deprecated feature was likely used in the MOFA2 package.
  Please report the issue at <https://github.com/bioFAM/MOFA2>.
---
Backtrace:
    ▆
 1. └─MOFA2::plot_dimred(model, method = "UMAP", color_by = "treatment_code")
 2.   └─ggplot2::guides(alpha = FALSE)
 3.     └─ggplot2:::deprecate_warn0("3.3.4", "guides(`<scale>` = 'cannot be `FALSE`. Use \"none\" instead')")

I think, it's required to change to p <- p + guides(alpha=none) here. I can create a pull request.