Fix README badge, remove bors.toml

Author: astapleton

.github/bors.toml

@@ -6,7 +6,7 @@
 <!-- [![Bors enabled](https://bors.tech/images/badge_small.svg)](https://app.bors.tech/repositories/12691) -->
 [![CI](https://github.com/stm32-rs/stm32h5xx-hal/workflows/Continuous%20integration/badge.svg)](https://github.com/stm32-rs/stm32h5xx-hal/actions)
 [![Crates.io](https://img.shields.io/crates/v/stm32h5xx-hal.svg)](https://crates.io/crates/stm32h5xx-hal)
-![Minimum rustc version](https://img.shields.io/badge/rustc-1.69.0+-yellow.svg)
+![Minimum rustc version](https://img.shields.io/badge/rustc-1.78.0+-yellow.svg)
 
 [_stm32h5xx-hal_](https://github.com/stm32-rs/stm32h5xx-hal) contains
 a hardware abstraction layer on top of the peripheral access API for

README.md

@@ -7,7 +7,6 @@ const re2 = /(1\.[0-9]{2}\.[0-9]{1})/g;
 const cargo_toml = 'Cargo.toml';
 const files = [
     'README.md',
-    '.github/bors.toml',
     '.github/workflows/ci.yml',
     '.github/workflows/clippy.yml',
     '.github/workflows/nightly.yml',