ci: Correct file paths and allow testing release.yml

[YDX-2147483647]

Continues #707

Test run: https://github.com/YDX-2147483647/BIThesis/actions/runs/20772442136

[Copilot]

Pull request overview

This PR corrects file paths throughout the CI/CD pipeline to reflect the project's src/ directory structure and enables testing of the release workflow without publishing an actual release.

Key changes:

• Corrects file paths from repository root to src/ directory for bithesis.dtx, bithesis.pdf, and *.cls files
• Adds workflow_dispatch trigger to allow manual testing of the release workflow
• Updates conditional logic to prevent actual uploads during test runs
• Fixes a spelling error in a comment

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
scripts/update_version.py	Updates the path to bithesis.dtx from root to src/bithesis.dtx
justfile	Adds new update-version recipe to expose the version update script for CI
.github/workflows/release.yml	Adds workflow_dispatch trigger, corrects artifact paths to src/ directory, adds conditionals to skip uploads during test runs, and fixes spelling in comment

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