WIP: Single SemVer bump per release

[s0ders]

What type of PR is this?

fix and refactor

What this PR does / why is it needed:

1. Makes the project compliant with the SemVer specification by only bumping once per release (choosing the higher type of bump for each release) as suggested by @dionysiusmarquis
2. Only fetch the latest reachable tag for each branch being processed, which removes various bug linked to the order in which branches are processed.
3. The parser not longer checks out to a branch to get its commits but uses its references, removes the issue of temporary files added in the repository before the program run (e.g., GPG key or whatever) disapearing after the check out and also makes the program more efficient.

Does this PR introduce a breaking change?

Yes, will upgrade the Go module version from v6 to v7.

Note to self

• Try to handle prerelease bumps
• Refactor the tests "framework" and tests in general for better maintainability

[codecov]

Codecov Report

❌ Patch coverage is 74.08638% with 78 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.30%. Comparing base (02194ad) to head (8b653b1).
⚠️ Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/parser/parser.go	70.53%	48 Missing and 23 partials ⚠️
internal/semver/semver.go	87.93%	6 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #217      +/-   ##
==========================================
- Coverage   80.56%   79.30%   -1.26%     
==========================================
  Files          14       14              
  Lines         602      807     +205     
==========================================
+ Hits          485      640     +155     
- Misses         70      101      +31     
- Partials       47       66      +19     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.