:sparkles: What kind of change does this PR introduce? (Bug fix, feature, docs update...)
Preview 11 added MAUI-specific implicit usings, so removed not needed explicit usings
Also it seems like referencing NuGets that were built using Preview 10 breaks the build (https://github.com/dotnet/maui/issues/3965), so removed Markup from Sample (it's not used anyway)
:arrow_heading_down: What is the current behavior?
:new: What is the new behavior (if this is a feature change)?
:sparkles: What kind of change does this PR introduce? (Bug fix, feature, docs update...)
:arrow_heading_down: What is the current behavior?
:new: What is the new behavior (if this is a feature change)?
:boom: Does this PR introduce a breaking change?
:bug: Recommendations for testing
:memo: Links to relevant issues/docs
684
:thinking: Checklist before submitting