Add 'dotnet-isolated:9.0' to staticwebapp schema (SchemaStore#4914)

The staticwebapp.config schema is missing support for the dotnet-isolated:9.0 runtime.

Author: tmcqueen

src/schemas/json/staticwebapp.config.json

@@ -605,6 +605,7 @@
             "dotnet-isolated:6.0",
             "dotnet-isolated:7.0",
             "dotnet-isolated:8.0",
+            "dotnet-isolated:9.0",
             "node:12",
             "node:14",
             "node:16",