Bump prometheus-net from 3.1.1 to 3.1.2

Bumps [prometheus-net](https://github.com/prometheus-net/prometheus-net) from 3.1.1 to 3.1.2.
- [Release notes](https://github.com/prometheus-net/prometheus-net/releases)
- [Changelog](https://github.com/prometheus-net/prometheus-net/blob/master/History)
- [Commits](https://github.com/prometheus-net/prometheus-net/compare/v3.1.1...v3.1.2)

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

OhmGraphite/OhmGraphite.csproj

@@ -31,7 +31,7 @@
     <PackageReference Include="Costura.Fody" Version="3.3.2" />
     <PackageReference Include="NLog.Config" Version="4.6.2" />
     <PackageReference Include="Npgsql" Version="4.0.6" />
-    <PackageReference Include="prometheus-net" Version="3.1.1" />
+    <PackageReference Include="prometheus-net" Version="3.1.2" />
     <PackageReference Include="Resourcer.Fody" Version="1.7.3" />
     <PackageReference Include="TopShelf" Version="4.2.0" />
     <PackageReference Include="Topshelf.NLog" Version="4.2.0" />