Bump System.Net.Http in /Samples/DotNetSdk/ObservationReportExporter

Bumps System.Net.Http from 4.3.0 to 4.3.4.

---
updated-dependencies:
- dependency-name: System.Net.Http
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Samples/DotNetSdk/ObservationReportExporter/packages.config

@@ -38,7 +38,7 @@
   <package id="System.Linq" version="4.3.0" targetFramework="net472" />
   <package id="System.Linq.Expressions" version="4.3.0" targetFramework="net472" />
   <package id="System.Memory" version="4.5.4" targetFramework="net472" />
-  <package id="System.Net.Http" version="4.3.0" targetFramework="net472" />
+  <package id="System.Net.Http" version="4.3.4" targetFramework="net472" />
   <package id="System.Net.Primitives" version="4.3.0" targetFramework="net472" />
   <package id="System.Net.Sockets" version="4.3.0" targetFramework="net472" />
   <package id="System.Numerics.Vectors" version="4.5.0" targetFramework="net472" />