Add dependabot to generated package

[lyashevska]

Description

• I have read the contribution guidelines
• This update is in line with what is recommended in the Python chapter of the Guide
• All user facing changes have been added to CHANGELOG.md

Related issues:

• Add dependabot to generated package #474

Instructions to review the pull request
Instructions to review the pull request

Install the requirements

cd $(mktemp -d --tmpdir py-tmpl-XXXXXX)
pip install pipx
pipx install copier

Test 1:
Run the command below and say 'yes' to dependabot question

copier copy --vcs-ref 474-add-dependabot-to-package https://github.com/nlesc/python-template test_yes

You should see the file below:

• .github/dependabot.yml

Test 2:
Run the command below and say 'no' to link checking question

copier copy --vcs-ref 474-add-dependabot-to-package https://github.com/nlesc/python-template test_no

You should not see the files below:

• .github/dependabot.yml

Test 3:

• Push the generated package to a GitHub repository
• Check if dependabot.yml workflow runs

[lyashevska]

add a question to copier.yaml

[lyashevska]

Need to add documentation about dependabot.