Bump Microsoft.CodeAnalysis.CSharp from 4.12.0 to 5.3.0 (#168)

Updated
[Microsoft.CodeAnalysis.CSharp](https://github.com/dotnet/roslyn) from
4.12.0 to 5.3.0.

<details>
<summary>Release notes</summary>

_Sourced from [Microsoft.CodeAnalysis.CSharp's
releases](https://github.com/dotnet/roslyn/releases)._

## 5.0.4

[Release](https://github.com/dotnet/core/releases/tag/v5.0.4)

## 5.0.2

[Release
Notes](https://github.com/dotnet/core/blob/master/release-notes/5.0/5.0.2/5.0.2.md)
[Install
Instructions](https://github.com/dotnet/core/blob/master/release-notes/5.0/5.0.2/5.0.2-install-instructions.md)

# Repos

* [Core](https://github.com/dotnet/core/releases/tag/v5.0.2)

## 5.0.1

[Release
Notes](https://github.com/dotnet/core/blob/master/release-notes/5.0/5.0.1/5.0.1.md)
[Install
Instructions](https://github.com/dotnet/core/blob/master/release-notes/5.0/5.0.1/5.0.1-install-instructions.md)

# Repo

* [Core](https://github.com/dotnet/core/releases/tag/v5.0.1)

Commits viewable in [compare
view](https://github.com/dotnet/roslyn/commits).
</details>

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Author: dependabot[bot]

Directory.Packages.props

@@ -15,7 +15,7 @@
     <PackageVersion Include="TextMateSharp.Grammars" Version="1.0.66" />
     <PackageVersion Include="FluentAvaloniaUI" Version="2.2.0" />
 
-    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.12.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging" Version="10.0.7" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.7" />