Bump Fantomas.Core in /src/server/ASTViewer

Bumps [Fantomas.Core](https://github.com/fsprojects/fantomas) from 6.3.0-alpha-003 to 6.3.0-alpha-004.
- [Release notes](https://github.com/fsprojects/fantomas/releases)
- [Changelog](https://github.com/fsprojects/fantomas/blob/main/CHANGELOG.md)
- [Commits](https://github.com/fsprojects/fantomas/commits)

---
updated-dependencies:
- dependency-name: Fantomas.Core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/server/ASTViewer/ASTViewer.fsproj

@@ -23,7 +23,7 @@
     <Compile Include="Program.fs" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="Fantomas.Core" Version="6.3.0-alpha-003" />
+    <PackageReference Include="Fantomas.Core" Version="6.3.0-alpha-004" />
     <PackageReference Include="FSharp.Core" Version="6.0.6" />
     <PackageReference Include="Thoth.Json.Net" Version="8.0.0" />
   </ItemGroup>