Bump NEST.JsonNetSerializer from 7.7.1 to 7.8.1

Bumps [NEST.JsonNetSerializer](https://github.com/elastic/elasticsearch-net) from 7.7.1 to 7.8.1.
- [Release notes](https://github.com/elastic/elasticsearch-net/releases)
- [Changelog](https://github.com/elastic/elasticsearch-net/blob/master/docs/breaking-changes.asciidoc)
- [Commits](elastic/elasticsearch-net@7.7.1...7.8.1)

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

src/Exceptionless.Core/Exceptionless.Core.csproj

@@ -31,10 +31,10 @@
     <PackageReference Include="McSherry.SemanticVersioning" Version="1.4.0" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="3.1.5" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="3.1.5" />
-    <PackageReference Include="NEST.JsonNetSerializer" Version="7.7.1" />
+    <PackageReference Include="NEST.JsonNetSerializer" Version="7.8.1" />
     <PackageReference Include="Stripe.net" Version="37.10.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="3.1.5" />
-    <PackageReference Include="NEST.JsonNetSerializer" Version="7.7.1" />
+    <PackageReference Include="NEST.JsonNetSerializer" Version="7.8.1" />
     <PackageReference Include="Stripe.net" Version="37.10.0" />
     <PackageReference Include="System.DirectoryServices" Version="4.7.0" />
     <PackageReference Include="UAParser" Version="3.1.44" />