chore: remove v prefix from release tags

[marandaneto]

💡 Motivation and Context

This ports the same release-workflow fix from posthog-go to posthog-dotnet. The current workflow creates GitHub releases as v<version>, but this repo should use plain semantic versions like 1.2.3 for the release tag/version instead.

💚 How did you test it?

• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/release.yml"); puts "yaml-ok"'
• git diff --check

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Added the release label to the PR
• Added exactly one version bump label: bump-patch, bump-minor, or bump-major

[github-actions]

posthog-dotnet Compliance Report

Date: 2026-04-20 07:15:06 UTC
Duration: 303ms

⚠️ Some Tests Failed

0/1 tests passed, 1 failed

---

Feature_Flags Tests

⚠️ 0/1 tests passed, 1 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	❌	45ms

Failures

request_payload.request_with_person_properties_device_id

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

[greptile-apps]

_{Reviews (1): Last reviewed commit: "chore: remove v prefix from release tags" | Re-trigger Greptile}