Merge pull request #906 from Timothyw0/developer/timothywang/enable-dotnet9

feature: Enable dotnet9 api runtime

Author: Timothyw0

schema/staticwebapp.config.json

@@ -590,6 +590,7 @@
             "dotnet-isolated:6.0",
             "dotnet-isolated:7.0",
             "dotnet-isolated:8.0",
+            "dotnet-isolated:9.0",
             "node:12",
             "node:14",
             "node:16",