587-Add version variable

[lyashevska]

Checklist before requesting a review

• I have read the contribution guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• All user facing changes have been added to CHANGELOG.md

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

List of related issues or pull requests**

Refs:

• Package version specified not used in conf.py #587

Instructions to review the pull request

Install the requirements

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

Create a new package using the template

copier copy --vcs-ref <YOUR_BRANCH> https://github.com/nlesc/python-template test_package

[fdiblen]

looks good. Thank you, @lyashevska!