Alpine-based GithubActions-only: added component rustfmt

Author: peter-lyons-kehl

.github/workflows/main.yml

@@ -19,7 +19,7 @@ jobs:
 
       - name: Tests and demos
         run: |
-          rustup component add clippy
+          rustup component add clippy rustfmt
           cargo clippy
           cargo fmt --check
           cargo doc --no-deps --quiet