Bump System.Text.Json from 6.0.5 to 8.0.4 in /ReadingBusesAPI

Bumps System.Text.Json from 6.0.5 to 8.0.4.

---
updated-dependencies:
- dependency-name: System.Text.Json
  dependency-type: direct:production
...

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

ReadingBusesAPI/ReadingBusesAPI.csproj

@@ -60,7 +60,7 @@ Get your own API Keys from: https://reading-opendata.r2p.com/api-service</Descri
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Text.Json" Version="6.0.5" />
+    <PackageReference Include="System.Text.Json" Version="8.0.4" />
   </ItemGroup>
 
 </Project>