CI uses deprecated Github actions

[Rotzbua]

Problem

CI uses deprecated Github actions.

Output

Following warning is thrown on every GH action run:

The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2, actions/cache@v2, actions/setup-python@v2. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

Solution

• Update GH actions.
• Add dependabot to keep track of updated actions.

Reference

https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/