ci: run clippy_check with rust stable

Author: notmandatory

.github/workflows/cont_integration.yml

@@ -118,9 +118,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-            # we pin clippy instead of using "stable" so that our CI doesn't break
-            # at each new cargo release
-            toolchain: "1.67.0"
+            toolchain: "stable"
             components: clippy
             override: true
       - name: Rust Cache