chore(rustc): bump minimum version

Author: kurnevsky

.github/workflows/rust.yml

@@ -14,7 +14,7 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
         rust:
           - stable
-          - 1.57
+          - 1.58
     steps:
     - uses: actions/checkout@v2
     - uses: actions-rs/toolchain@v1

README.md

@@ -30,7 +30,7 @@ issue / pull request should be filled on the reference repository.
 [CONTRIBUTING.md](/CONTRIBUTING.md).
 
 ## Building
-Fairly simple. First, install [Rust] >= 1.57 and a C compiler ([Build Tools
+Fairly simple. First, install [Rust] >= 1.58 and a C compiler ([Build Tools
 for Visual Studio][VSBuild] on Windows, GCC or Clang on other platforms).
 
 Then you can build the debug version with