update github workflow for MSRV

Author: sunshowers

.github/workflows/ci.yml

@@ -38,8 +38,8 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
-        # 1.58 is the MSRV
-        rust-version: [ 1.58, stable ]
+        # 1.60 is the MSRV
+        rust-version: [ 1.60, stable ]
       fail-fast: false
     env:
       RUSTFLAGS: -D warnings