Fixes and Functionality:

- Fixing requestHeaders.Authorization ([#3287](https://github.com/axios/axios/pull/3287))

- Fixing node types ([#3237](https://github.com/axios/axios/pull/3237))

- Fixing axios.delete ignores config.data ([#3282](https://github.com/axios/axios/pull/3282))

- Revert "Fixing overwrite Blob/File type as Content-Type in browser. (#1773)" ([#3289](https://github.com/axios/axios/pull/3289))

- Fixing an issue that type 'null' and 'undefined' is not assignable to validateStatus when typescript strict option is enabled ([#3200](https://github.com/axios/axios/pull/3200))

Internal and Tests:

- Lock travis to not use node v15 ([#3361](https://github.com/axios/axios/pull/3361))

Documentation:

- Fixing simple typo, existant -> existent ([#3252](https://github.com/axios/axios/pull/3252))

- Fixing typos ([#3309](https://github.com/axios/axios/pull/3309))

Huge thanks to everyone who contributed to this release via code (authors listed below) or via reviews and triaging on GitHub:

- Allan Cruz <57270969+Allanbcruz@users.noreply.github.com>

- George Cheng <Gerhut@GMail.com>

- Jay <jasonsaayman@gmail.com>

- Kevin Kirsche <Kev.Kirsche+GitHub@gmail.com>

- Remco Haszing <remcohaszing@gmail.com>

- Taemin Shin <cprayer13@gmail.com>

- Tim Gates <tim.gates@iress.com>

- Xianming Zhong <chinesedfan@qq.com>