bump MSRV to 1.57

const-oid v0.9.0, which is a dependency through ecdsa 0.14
requires Rust 1.57

Author: daniestevez

.github/workflows/rust.yml

@@ -44,13 +44,13 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Install toolchain
-      run: rustup install 1.56.0
+      run: rustup install 1.57.0
     - name: Doc
-      run: cargo +1.56.0 doc --features galmon
+      run: cargo +1.57.0 doc --features galmon
     - name: Build
-      run: cargo +1.56.0 build --verbose --features galmon
+      run: cargo +1.57.0 build --verbose --features galmon
     - name: Run tests
-      run: cargo +1.56.0 test --verbose --features galmon
+      run: cargo +1.57.0 test --verbose --features galmon
 
   galmon:
     name: Galmon

README.md

@@ -124,7 +124,7 @@ functionality and usability of galileo-osnma:
 
 ## Minimum Supported Rust Version
 
-Rust **1.56** or higher.
+Rust **1.57** or higher.
 
 Minimum supported Rust version can be changed in the future, but it will be done
 with a minor version bump.