ci: increase MSRV due to dependencies

Author: dr-orlovsky

.github/workflows/build.yml

@@ -74,7 +74,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        toolchain: [ nightly, beta, stable, 1.59.0 ]
+        toolchain: [ nightly, beta, stable, 1.66.0 ]
     steps:
       - uses: actions/checkout@v2
       - name: Install rust ${{ matrix.toolchain }}

README.md

@@ -25,7 +25,7 @@ possible applications designed by Giacomo Zucco. It was shaped into a protocol-
 level design by Dr Maxim Orlovsky with a big input from the community and
 implemented by him as this set of libraries.
 
-Minimum supported rust version for the library (MSRV) is 1.59 and 2021 rust 
+Minimum supported rust version for the library (MSRV) is 1.66 and 2021 rust 
 edition.