chore(deps): update dependency csharpasyncgenerator.tool to v0.21.1 (#22)

Author: renovate[bot]

.config/dotnet-tools.json

@@ -3,7 +3,7 @@
   "isRoot": true,
   "tools": {
     "csharpasyncgenerator.tool": {
-      "version": "0.21.0",
+      "version": "0.22.0",
       "commands": [
         "async-generator"
       ]