Bump greenlet from 0.4.17 to 1.1.1

Bumps [greenlet](https://github.com/python-greenlet/greenlet) from 0.4.17 to 1.1.1.
- [Release notes](https://github.com/python-greenlet/greenlet/releases)
- [Changelog](https://github.com/python-greenlet/greenlet/blob/master/CHANGES.rst)
- [Commits](https://github.com/python-greenlet/greenlet/compare/0.4.17...1.1.1)

---
updated-dependencies:
- dependency-name: greenlet
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

README.md

@@ -1,5 +1,3 @@
-## This project is no longer maintained. Visit [this repo](https://github.com/TeamPiped/Piped) for an alternative.
-
 <p align="center"> <img width="700" src="app/static/img/banner.png"> </img></p> 
 <p align="center">
    <a href="https://www.gnu.org/licenses/gpl-3.0"><img alt="License: GPL v3" src="https://img.shields.io/badge/License-AGPLv3-blue.svg"></img></a>

requirements.txt

@@ -13,7 +13,7 @@ Flask-Migrate==2.5.3
 Flask-SQLAlchemy==2.4.4
 Flask-WTF==0.14.3
 gevent==20.9.0
-greenlet==0.4.17
+greenlet==1.1.1
 idna==2.10
 itsdangerous==1.1.0
 Jinja2==2.11.3