chore(2.x): release 2.21.0

[github-actions]

🤖 I have created a release beep boop

2.21.0 (2026-06-24)

Features

• OnConflict: index-inference predicate for ON CONFLICT (Postgres/SQLite) (#258) (bdd2cea)

Bug Fixes

• MySQL: omit row alias on upsert DO NOTHING — the alias made the no-op col = col ambiguous at runtime (bdd2cea)
• Postgres: unquote EXCLUDED in upsert DO UPDATE — quoted "EXCLUDED" broke every update-branch upsert at runtime (bdd2cea)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.69%. Comparing base (bdd2cea) to head (7262519).
⚠️ Report is 1 commits behind head on 2.x.

Additional details and impacted files

@@            Coverage Diff            @@
##                2.x     #259   +/-   ##
=========================================
  Coverage     95.69%   95.69%           
  Complexity     2067     2067           
=========================================
  Files           140      140           
  Lines          5835     5835           
=========================================
  Hits           5584     5584           
  Misses          251      251           

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[github-actions]

🤖 Release is at https://github.com/cycle/database/releases/tag/2.21.0 🌻