make copyright year/owner spacing consistently double spaced

[sjvrijn]

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
• My changes generate no new warnings

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:

• GPLv3 has inconsistent use of spaces #685

Describe the changes made in this pull request

Made spacing consistent in GPLv3 license text.

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, choosing the GPLv3 license

copier copy --vcs-ref 685-gplv3-spacing https://github.com/nlesc/python-template test_package

• Confirm the spacing is now consistent at lines 635 and 655 of the LICENSE file

[fdiblen]

Thank you, @sjvrijn!
Looks good to me.
PS: Sorry for the late reaction.