jest.config,CI: convert to typescript

The --config parameter is included due to the fact that tsc
creates a jest.config.js file. If this parameter is not
specified, we encounter an error stating:
"Multiple configurations found".

Also we need to install ts-node:

```
  Error: Jest: 'ts-node' is required for the TypeScript configuration files. Make sure it is installed
```

.github/workflows/CI.yml

@@ -133,7 +133,7 @@ jobs:
       - name: Install yarn
         run: |
           npm install --global yarn
-          yarn add --dev jest typescript ts-jest @types/jest
+          yarn add --dev jest typescript ts-jest @types/jest ts-node
       - name: Run typescript compiler
         run: npx tsc
       - name: Print versions
@@ -144,7 +144,7 @@ jobs:
           npx commitlint --version
           yarn --version
       - name: Run tests to validate our plugins
-        run: yarn jest
+        run: yarn jest --config jest.config.ts
 
   sanity-check:
     name: Sanity check

jest.config.ts

@@ -0,0 +1,8 @@
+import type { Config } from "@jest/types";
+
+const config: Config.InitialOptions = {
+    preset: "ts-jest",
+    testEnvironment: "node",
+};
+
+export default config;