chore(deps): update dependency prometheus.client to v4.2.0

Author: renovate-bot

src/Prometheus.Client.MetricServer/Prometheus.Client.MetricServer.csproj

@@ -31,7 +31,7 @@
     </None>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="Prometheus.Client" Version="4.1.0" />
+    <PackageReference Include="Prometheus.Client" Version="4.2.0" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.1'">