Bump ApprovalTests from 5.9.0 to 6.0.0 in /src

Bumps [ApprovalTests](https://github.com/approvals/ApprovalTests.Net) from 5.9.0 to 6.0.0.
- [Release notes](https://github.com/approvals/ApprovalTests.Net/releases)
- [Commits](https://github.com/approvals/ApprovalTests.Net/commits)

---
updated-dependencies:
- dependency-name: ApprovalTests
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

src/GitReleaseManager.Core.Tests/GitReleaseManager.Core.Tests.csproj

@@ -18,7 +18,7 @@
  <PrivateAssets>all</PrivateAssets>
  </PackageReference>
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
- <PackageReference Include="ApprovalTests" Version="5.9.0" />
+ <PackageReference Include="ApprovalTests" Version="6.0.0" />
  <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
  <PrivateAssets>all</PrivateAssets>

src/GitReleaseManager.Tests/GitReleaseManager.Tests.csproj

@@ -18,7 +18,7 @@
  <PrivateAssets>all</PrivateAssets>
  </PackageReference>
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
- <PackageReference Include="ApprovalTests" Version="5.9.0" />
+ <PackageReference Include="ApprovalTests" Version="6.0.0" />
  <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
  <PrivateAssets>all</PrivateAssets>