bumped MSRV

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.68.2
       - run: cargo check --release
 
   cross-check: