bump FakeItEasy to v5.4.0

Author: jetersen

test/GitLabApiClient.Test/GitLabApiClient.Test.csproj

@@ -11,7 +11,7 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="1.1.0" />
-    <PackageReference Include="FakeItEasy" Version="5.2.0" />
+    <PackageReference Include="FakeItEasy" Version="5.4.0" />
     <PackageReference Include="FluentAssertions" Version="5.9.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
     <PackageReference Include="xunit" Version="2.4.1" />