1.15.0-rc3

* BREAKING
  * Upgrade to the latest version of golang-jwt and increase minimum go to 1.15 (#16590) (#16606)
* SECURITY
  * Upgrade to the latest version of golang-jwt and increase minimum go to 1.15 (#16590) (#16606)
  * Correctly create of git-daemon-export-ok files (#16508) (#16514)
  * Don't show private user's repo in explore view (#16550) (#16554)
  * Update node tar dependency to 6.1.6 (#16622) (#16623)
* API
  * Swagger AccessToken fixes (#16574) (#16597)
  * Set AllowedHeaders on API CORS handler (#16524) (#16618)
* BUGFIXES
  * Restore Accessibility for Dropdown (#16576) (#16617)
  * Pass down SignedUserName down to AccessLogger context (#16605) (#16616)
  * Fix table alignment in markdown (#16596) (#16602)
  * Fix 500 on first wiki page (#16586) (#16598)
  * Lock goth/gothic and Re-attempt OAuth2 registration on login if registration failed at startup (#16564) (#16570)
  * Upgrade levelqueue to v0.4.0 (#16560) (#16561)
  * Handle too long PR titles correctly (#16517) (#16549)
  * Fix data race in bleve indexer (#16474) (#16509)
  * Restore CORS on git smart http protocol (#16496) (#16506)
  * Fix race in log (#16490) (#16505)
  * Fix prepareWikiFileName to respect existing unescaped files (#16487) (#16498)
  * Make cancel from CatFileBatch and CatFileBatchCheck wait for the command to end (#16479) (#16480)
  * Update notification table with only latest data (#16445) (#16469)
  * Revert to use alpine 3.13 (#16451) (#16452)
  * Fix crash following ldap authentication update (#16447) (#16448)
  * Fix direct creation of external users on admin page (partial #16612) (#16613)
  * Prevent 500 on draft releases without tag (#16634) (#16636)