Purpose

As discussed in #1156 and #846, this adds two features to the version_variables configuration:

1. allow the @ separator between the search string and the version within the files
2. allow a single "v" without any spaces to precede the version

E.g. when running psr with the following configuration

[tool.semantic_release]
version_variables = ["my-versions.txt:version"]

and there is a my-versions.txt with content

version@v1.2.3

and the new version is 2.3.4 the content of my-versions.txt will be:

version@v2.3.4

Rationale

Simple adaption of the regex did the trick

How did you test?

Unittesting was not easy as the implementation was entangled with other code. Therefore I did multiple commits:

• 49a9366 -> adapt the regex. This is the whole implementation of the features
• c3804fe -> documentation
• 47afae9 -> here i entangled the regex building from the config parsing. This way i was able to test the module on its own
• 456a2bf -> contains the unittests. This is my first time working with pytest. If i did something wrong, please let me know

Regarding the e2e tests: The tests are massive. I don't know where (and how i can expand those). I you point me to the right direction, i will add those tests.

How to Verify

The new documentation gives an example how to configure

PR Completion Checklist

• Reviewed & followed the Contributor Guidelines

• Changes Implemented & Validation pipeline succeeds

• Commits follow the Conventional Commits standard
  and are separated into the proper commit type and scope (recommended order: test, build, feat/fix, docs)

• Appropriate Unit tests added/updated

• Appropriate End-to-End tests added/updated

• Appropriate Documentation added/updated and syntax validated for sphinx build (see Contributor Guidelines)