Prevent inappropriate @types/node bumps from Dependabot

The project has a dependency on the `@types/node` package. That package follows the major version of Node.js.

https://stackoverflow.com/questions/42035263/relationship-between-the-version-of-node-js-and-the-version-of-types-node

Since we are now using Node.js 16.x for the development of the project, we must also use the ^16.x series of
`@types/node`.

Because there are 17.x versions of the `@types/node` package available, Dependabot would submit unwanted PRs to bump the
dependency to those versions. This configuration prevents that. Dependabot will continue to submit PRs for bumps to any
new minor or patch releases made within the current major version series.

Since this configuration prevents Dependabot from submitting major version bumps, The `@types/node` dependency version
must be bumped manually when we update to using a new major version of Node.js for the development of this project.

Reference:
https://docs.github.com/en/code-security/supply-chain-security/keeping-your-dependencies-updated-automatically/configuration-options-for-dependency-updates#specifying-dependencies-and-versions-to-ignore

Author: per1234

.github/dependabot.yml

@@ -17,3 +17,9 @@ updates:
       interval: daily
     labels:
       - "topic: infrastructure"
+    ignore:
+      - dependency-name: "@types/node"
+        # @types/node should be kept in sync with the major version of Node.js that is in use.
+        # So we only want automated updates for minor and patch releases of this dependency.
+        update-types:
+          - "version-update:semver-major"