.github/clippy: ignore clippy errors on v0.8.X

Newer toolchains introduce clippy lints that we can't properly
verify will still compile in old packages and setups if addressed,
since clippy could easily suggest code that won't work there, so
make the clippy CI tests not required to pass CI on 0.8.X releases.

Author: unleashed

.github/workflows/clippy.yaml

@@ -11,6 +11,7 @@ on:
 jobs:
   clippy_check:
     runs-on: ubuntu-latest
+    continue-on-error: true
     steps:
       - uses: actions/checkout@v2
         with: