ci: use native github actions for pull request checks

.github/workflows/check.yml

@@ -4,8 +4,8 @@ on:
   push:
     branches:
       - main
-      - trying
       - staging
+  pull_request:
 
 jobs:
   check:

README.md

@@ -1,4 +1,3 @@
-[![Bors enabled](https://bors.tech/images/badge_small.svg)](https://app.bors.tech/repositories/33905)
 [![MIT License](https://img.shields.io/github/license/divnix/devos)][mit]
 [![NixOS](https://img.shields.io/badge/NixOS-unstable-blue.svg?style=flat&logo=NixOS&logoColor=white)](https://nixos.org)
 [![Chat](https://img.shields.io/badge/chat-join%20us-brightgreen.svg?style=flat&logo=matrix&logoColor=white)](https://matrix.to/#/#devos:nixos.org)

bors.toml

@@ -1,7 +0,0 @@
-status = [ "check" ]
-
-required_approvals = 1
-
-up_to_date_approvals = true
-
-delete_merged_branches = true

doc/CONTRIBUTING.md

@@ -1,6 +1,6 @@
 # TL;DR;
 - **Target Branch**: `main`
-- **Merge Policy**: [`bors`][bors] is always right (→ `bors try`)
+- **Merge Policy**: green check: merge away. yellow circle: have patience. red x: try again.
 - **Docs**: every change set is expected to contain doc updates
 - **Commit Msg**: be a poet! Comprehensive and explanatory commit messages 
   should cover the motivation and use case in an easily understandable manner
@@ -12,5 +12,3 @@
 - **Hooks**: please `git commit` within the devshell
 - **Fail Early**: please run `check-all` from within the devshell on your local machine
 
-[bors]: https://bors.tech
-