Split badges in README to have render better on GitHub

[matthewfeickert]

GitHub has changed some of the ways that they render files in the last months, and one of those changes means that if badges are displayed in a .rst file like they are in the README now

hepdata-validator/README.rst

Lines 5 to 31 in bfcd4fd

	.. image:: https://github.com/HEPData/hepdata-validator/actions/workflows/ci.yml/badge.svg?branch=main
	:target: https://github.com/HEPData/hepdata-validator/actions?query=branch%3Amain
	:alt: GitHub Actions Build Status
	.. image:: https://coveralls.io/repos/github/HEPData/hepdata-validator/badge.svg?branch=main
	:target: https://coveralls.io/github/HEPData/hepdata-validator?branch=main
	:alt: Coveralls Status
	.. image:: https://img.shields.io/github/license/HEPData/hepdata-validator.svg
	:target: https://github.com/HEPData/hepdata-validator/blob/main/LICENSE.txt
	:alt: License
	.. image:: https://img.shields.io/github/release/hepdata/hepdata-validator.svg?maxAge=2592000
	:target: https://github.com/HEPData/hepdata-validator/releases
	:alt: GitHub Releases
	.. image:: https://img.shields.io/pypi/v/hepdata-validator
	:target: https://pypi.org/project/hepdata-validator/
	:alt: PyPI Version
	.. image:: https://img.shields.io/github/issues/hepdata/hepdata-validator.svg?maxAge=2592000
	:target: https://github.com/HEPData/hepdata-validator/issues
	:alt: GitHub Issues
	.. image:: https://readthedocs.org/projects/hepdata-validator/badge/?version=latest
	:target: https://hepdata-validator.readthedocs.io/en/latest/?badge=latest
	:alt: Documentation Status

they will be too much for a single line and GitHub will instead decide to display each one on its own line, which isn't great.

To get around this, myself and others (c.f. TDAmeritrade/stumpy@86d7015) have noticed that if a

|PyPI Version| 

.. |PyPI Version| image:: https://img.shields.io/pypi/v/hepdata-validator 
   :target: https://pypi.org/project/hepdata-validator/ 
   :alt: PyPI Version 

format is used then things render as intended.

[GraemeWatt]

@matthewfeickert : thanks for the tip! I had noticed the change in the display of the badges, but I hadn't investigated how to fix it. Now addressed by PR #61.