Add regression tests for changelog text manipulation

[nwiltsie]

Description

This is what I get for being so terse with #6 and #7...

This actually fixes the issue I ran into with /~https://github.com/uclahs-cds/tool-BoutrosLab-utils/pull/23. The auto-generated links at the end had extra vs:

[0.2.0]: /~https://github.com/uclahs-cds/tool-BoutrosLab-utils/compare/vv0.0.1...v0.2.0
[v0.0.1]: /~https://github.com/uclahs-cds/tool-BoutrosLab-utils/releases/tag/vv0.0.1

I thought I fixed that with #7, but that would have resulted in these links (the first one is broken):

[0.2.0]: /~https://github.com/uclahs-cds/tool-BoutrosLab-utils/compare/v0.0.1...0.2.0
[v0.0.1]: /~https://github.com/uclahs-cds/tool-BoutrosLab-utils/releases/tag/v0.0.1

The real issue was that the changelog included v0.0.1 as a version, which is what this PR fixes.

---

The README now includes a note that versions must begin with a digit, and that the corresponding git tags must begin with a v. The actual fix for #6 is to strip leading vs from versions in the changelog, and go back to appending that v when constructing the tag links.

To make this more explicit I added some regression tests with bundled changelog files. The "original" file includes non-standard formatting and v2.5.0 as a version. The formatted file is the result of parsing and re-serializing the original, and shows that v2.5.0 is changed to 2.5.0. Finally, there is an updated file with a minor version bump.

Diff between `original` and `formatted`

--- tests/resources/original.md	2024-09-23 12:32:40
+++ tests/resources/formatted.md	2024-09-17 13:39:37
@@ -4,39 +4,33 @@

 This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

----
+## [Unreleased]

-## Unreleased
+### Security

-### Added
+- Security item

-### Security
+## [2.5.1] - 2024-02-01

-* Security item
+### Added

-## 2.5.1 - 2024-02-01
+- Add one
+- Add two

-## fix
+### Fixed

 - Fix one
 - Fix two

+## [2.5.0] - 2024-01-01

+Stray text

+### Changed

-### add
-
-* Add one
-* Add two
-
----
-
-
-## [v2.5.0] - 2024-01-01
-
-## change
-
 - Change one
 - Change two

-Stray text
+[2.5.0]: /~https://github.com/foo/bar/releases/tag/v2.5.0
+[2.5.1]: /~https://github.com/foo/bar/compare/v2.5.0...v2.5.1
+[unreleased]: /~https://github.com/foo/bar/compare/v2.5.1...HEAD

Diff between `formatted` and `2.5.3`

--- tests/resources/formatted.md	2024-09-17 13:39:37
+++ tests/resources/2.5.3.md	2024-09-17 13:39:37
@@ -4,7 +4,7 @@

 This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

-## [Unreleased]
+## [2.5.3] - 2024-05-05

 ### Security

@@ -33,4 +33,4 @@

 [2.5.0]: /~https://github.com/foo/bar/releases/tag/v2.5.0
 [2.5.1]: /~https://github.com/foo/bar/compare/v2.5.0...v2.5.1
-[unreleased]: /~https://github.com/foo/bar/compare/v2.5.1...HEAD
+[2.5.3]: /~https://github.com/foo/bar/compare/v2.5.1...v2.5.3

Checklist

• This PR does NOT contain Protected Health Information (PHI). A repo may need to be deleted if such data is uploaded.
  Disclosing PHI is a major problem¹ - Even a small leak can be costly².

• This PR does NOT contain germline genetic data³, RNA-Seq, DNA methylation, microbiome or other molecular data⁴.

• This PR does NOT contain other non-plain text files, such as: compressed files, images (e.g. .png, .jpeg), .pdf, .RData, .xlsx, .doc, .ppt, or other output files.

  To automatically exclude such files using a .gitignore file, see here for example.

• I have read the code review guidelines and the code review best practice on GitHub check-list.

• I have set up or verified the main branch protection rule following the github standards before opening this pull request.

• The name of the branch is meaningful and well formatted following the standards, using [AD_username (or 5 letters of AD if AD is too long)]-[brief_description_of_branch].

• I have added the major changes included in this pull request to the CHANGELOG.md under the next release version or unreleased, and updated the date.

Footnotes

1. UCLA Health reaches $7.5m settlement over 2015 breach of 4.5m patient records ↩

2. The average healthcare data breach costs $2.2 million, despite the majority of breaches releasing fewer than 500 records. ↩

3. Genetic information is considered PHI.
   Forensic assays can identify patients with as few as 21 SNPs ↩

4. RNA-Seq, DNA methylation, microbiome, or other molecular data can be used to predict genotypes (PHI) and reveal a patient's identity. ↩