Apply suggestion from @maartenba

Author: maartenba

src/content/docs/identityserver/upgrades/identityserver4-to-duende-identityserver-v7.mdx

@@ -386,7 +386,7 @@ The IdentityModel package was renamed to Duende IdentityModel and needs updating
 
 ```diff lang="xml" title=".csproj"
 - <PackageReference Include="IdentityModel" Version="x.y.z" />
-+ <PackageReference Include="Duende.IdentityModel" Version="7.0.0" />
++ <PackageReference Include="Duende.IdentityModel" Version="7.1.0" />
 ```
 
 ### Step 3: Update Namespaces