revert: remove v0.6.0 release (no user-facing changes)

The v0.6.0 release contained only infrastructure changes (CI
workflows, badges, review scripts, test fixes). The only
user-facing file changed was api_clients.py, which was modified
to fix the Gitea review API event name — an internal CI fix,
not a user-facing feature.

Reverting the version bump and CHANGELOG entry. The tag and
release have been deleted from the remote.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -2,20 +2,6 @@
 
 All notable changes to this project will be documented in this file.
 
-## [0.6.0] - 2026-06-21
-
-### Features
-
-- Add self-updating quality badges to README
-- Enforce mandatory PR reviews with automated checks
-
-### Bug Fixes
-
-- Bridge test suite gaps — lint scripts, include integration tests
-- Badge regex patterns and doc_coverage double-percent
-- Generate self-contained SVG badges instead of shields.io JSON
-- Auto_merge handles single-token workflow (self-approval)
-
 ## [0.5.0] - 2026-06-21
 
 ### Packaging

src/gitea_runner_manager/__init__.py

@@ -1,3 +1,3 @@
 """Gitea Runner Manager — lean CLI for managing Gitea Actions runners."""
 
-__version__ = "0.6.0"
+__version__ = "0.5.0"