Fix CI caching

Author: cberner

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
                 ~/.cargo/registry/cache/
                 ~/.cargo/git/db/
                 target/
-            key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml', '.github/workflows/*.yml', 'rust-toolchain') }}
+            key: ${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/Cargo.toml', '.github/workflows/*.yml', 'rust-toolchain') }}
 
       - name: Check for forbidden words
         if: runner.os != 'Windows'