Release do-nothing script: correct handling of patch releases

[trexfeathers]

🚀 Pull Request

Description

• Significantly re-works the release do-nothing script
• Corrects how the release do-nothing script handles patch releases
• Additional advice for how to patch multiple releases in one 'go'
• Automated testing for the release do-nothing script

To-do

• Find a solution to installing nothing for testing the do-nothing script
  • Include in dependencies?
  • Install on the fly?

  • iris/tools/release_do_nothing.py

    Lines 22 to 29 in bb248bc

    	try:
    	from nothing import Progress
    	except ImportError:
    	install_message = (
    	"This script requires the `nothing` package to be installed:\n"
    	"pip install git+https://github.com/SciTools-incubator/nothing.git"
    	)
    	raise ImportError(install_message)

• Finish writing the automated tests
• Action any corrections that the testing highlights
• Find an alternative term to series, which is meaningful to everyone while not being ambiguous

---

Consult Iris pull request check list

---

Add any of the below labels to trigger actions on this PR:

• benchmark_this Request that this pull request be benchmarked to check if it introduces performance shifts

[scitools-ci]

• Please see: SciTools/.github#191

[trexfeathers]

Oops

SciTools/.github#191 (comment)

[trexfeathers]

Remotes do not have to end with .git. Would it still be unambiguous enough without?