bump stable toolchain version for CI

Author: klensy

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Install toolchain
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.70.0
+          toolchain: 1.73.0
           override: true
           components: rustfmt, clippy