Bump Eto.Platform.Gtk and Eto.Forms

Bumps [Eto.Platform.Gtk](https://github.com/picoe/Eto) and [Eto.Forms](https://github.com/picoe/Eto). These dependencies needed to be updated together.

Updates `Eto.Platform.Gtk` from 2.7.2 to 2.8.2
- [Release notes](https://github.com/picoe/Eto/releases)
- [Commits](picoe/Eto@2.7.2...2.8.2)

Updates `Eto.Forms` from 2.7.2 to 2.8.2
- [Release notes](https://github.com/picoe/Eto/releases)
- [Commits](picoe/Eto@2.7.2...2.8.2)

---
updated-dependencies:
- dependency-name: Eto.Platform.Gtk
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: Eto.Forms
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Atomic.Gtk/Atomic.Gtk.csproj

@@ -8,7 +8,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="Eto.Platform.Gtk" Version="2.7.2" />
+      <PackageReference Include="Eto.Platform.Gtk" Version="2.8.2" />
     </ItemGroup>
 
     <ItemGroup>