Add transformer wrapper for yaml-jest to be compatible with v28,

following the hint at https://github.com/sumwatshade/jest-transform-yaml/issues/19#issuecomment-1232857013

client/tests/jest/jest.config.js

@@ -184,9 +184,9 @@ module.exports = {
     transform: {
         ...tsjPreset.transform,
         "^.+\\.js$": "babel-jest",
-        ".*\\.(vue)$": "@vue/vue2-jest",
-        "\\.yml$": "yaml-jest",
-        "\\.txt$": "jest-raw-loader",
+        "^.*\\.(vue)$": "@vue/vue2-jest",
+        "^.+\\.ya?ml$": "<rootDir>/tests/jest/yaml-jest.js",
+        "^.+\\.txt$": "jest-raw-loader",
     },
 
     // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation

client/tests/jest/yaml-jest.js

@@ -0,0 +1,13 @@
+const transformer = require("yaml-jest").default
+
+const newTransformer = {
+  ...transformer,
+  process: function (...params) {
+    return {
+      code: transformer?.process(...params),
+      map: null,
+    }
+  },
+}
+
+module.exports = newTransformer