Bump AltCover from 8.8.21 to 8.8.53 (#1754)

Bumps [AltCover](https://github.com/SteveGilham/altcover) from 8.8.21 to 8.8.53.
- [Release notes](https://github.com/SteveGilham/altcover/releases)
- [Changelog](https://github.com/SteveGilham/altcover/blob/master/ReleaseNotes.md)
- [Commits](SteveGilham/altcover@release/v8.8.21...release/v8.8.53)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

UnitTests/UnitTests.csproj

@@ -23,7 +23,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="AltCover" Version="8.8.21" />
+    <PackageReference Include="AltCover" Version="8.8.53" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="nunit" Version="4.1.0" />