Fix publish env var.

Author: ehuss

.github/workflows/publish-mdbook-spec.yml

@@ -18,7 +18,7 @@ jobs:
         run: cargo test
       - name: Publish
         env:
-          CRATES_IO_TOKEN: ${{ secrets.CRATES_IO_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CRATES_IO_TOKEN }}
         run: |
           version=`sed -n -E 's/^version = "(.*)"/\1/p' Cargo.toml`
           cargo publish --no-verify