Update dotnet-tools.json - slngen to 11.2.6 (#442)

Author: michael-hawker

.config/dotnet-tools.json

@@ -15,10 +15,10 @@
       ]
     },
     "microsoft.visualstudio.slngen.tool": {
-      "version": "11.2.3",
+      "version": "11.2.6",
       "commands": [
         "slngen"
       ]
     }
   }
-}
+}