Fix trailing comma in Caching.slnf (#31438)

Author: Youssef1313

src/Caching/Caching.slnf

@@ -5,7 +5,7 @@
       "src\\Caching\\SqlServer\\src\\Microsoft.Extensions.Caching.SqlServer.csproj",
       "src\\Caching\\SqlServer\\test\\Microsoft.Extensions.Caching.SqlServer.Tests.csproj",
       "src\\Caching\\StackExchangeRedis\\src\\Microsoft.Extensions.Caching.StackExchangeRedis.csproj",
-      "src\\Caching\\StackExchangeRedis\\test\\Microsoft.Extensions.Caching.StackExchangeRedis.Tests.csproj",
+      "src\\Caching\\StackExchangeRedis\\test\\Microsoft.Extensions.Caching.StackExchangeRedis.Tests.csproj"
     ]
   }
-}
+}